Information Recording Medium Wherein Stream Convertible at High-Speed is Recorded, and Recording Apparatus and Recording Method Therefor

ABSTRACT

An information recording medium capable of converting a stream including seamless connection, which is recorded in a constrained format allowing format conversion from a first format (MPEG-TS) to a second format (MPEG-PS), into a second stream, and an apparatus and method for recording information in the information recording medium. The constrained format is provided for enabling conversion from a first format (for example, MPEG transport stream) to a second format (for example, MPEG program stream). Seamless playback is performed by using a third system stream (Bridge-VOB), which is composed of each of the parts the two seamlessly connected system streams. A video information presentation time by data management unit (Capsule) at a third system stream terminal is greater than or equal to 0.4 second and less than or equal to 1 second, according to the constrained format.

TECHNICAL FIELD

The present invention relates to an information recording medium capableof being recorded or reproduced and storing multimedia data includingdata in various kinds of formats, such as moving picture, still picture,audio data, and data broadcasting. More particularly, the inventionrelates to a recording medium which records multimedia data in aconstrained format that enables conversion from a format of the recordeddata to a different format. The invention also relates to an apparatusand method for recording data to such an information recording medium.

BACKGROUND ART

Rewritable optical discs have had a maximum storage capacity ofapproximately 650 MB, but this limit has been pushed to severalgigabytes by the introduction of DVD-RAM discs, a phase-change type ofstorage medium. Used in conjunction with practical implementations ofMPEG (particularly MPEG-2), a digital AV data encoding standard, DVD-RAMis not limited to computer applications and will soon find widespreaduse as a recording and playback medium in the audio-video (AV) and evenhome entertainment industries.

With the start of digital broadcasts in recent Japan, it has becomepossible to multiplex and simultaneously transmit the video, audio, anddata portions of plural programs to the MPEG transport stream(“MPEG-TS”). Digital broadcast recorders using hard discs or DVD mediato record these programs are also available. As a standard for such aninformation recording medium in the next generation, which is suitablefor recording digital broadcasting, there is Blu-ray Disc standard (“BDstandard”).

The next generation digital broadcast recorder (Blu-ray Disc recorder)does not convert broadcasted MPEG-TS but records mainly data in MPEG-TSformat according to a format of digital broadcasting. The nextgeneration digital broadcast recorder records AV stream in MPEG-TSformat even when self-recording AV data received from external. This isbecause it becomes unnecessary for the recorder to handle both MPEGprogram stream (“MPEG-PS”) and MPEG transport stream.

However, because the current DVD standards (including the DVD-Videostandard, DVD-Audio standard, DVD Video Recording standard, and DVDStream Recording standard) use the MPEG-PS for recording AV stream,MPEG-TS to MPEG-PS conversion (“TS2PS conversion”) is required in orderto convert content recorded in the MPEG-TS format, such as by theabove-noted next generation digital broadcast recorder, to the DVD-Videoformat, for example.

Converting a stream multiplexed to the MPEG-TS to MPEG-PS, however,involves a complex recalculation for decoder buffer management, theTS2PS conversion is time-consuming, and often involves re-encoding theelementary stream, resulting in degraded image quality and soundquality.

Against these problems, some solving methods are proposed (see patentdocument 1, for example).

Patent document 1: JP-A-2003-228922

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

However a method that enables easy conversion from an MPEG-TS to anMPEG-PS format when converting AV stream including a seamless connectionpoint for enabling continuous presentation of two AV streams has yet tobe proposed.

The present invention is directed to solving this problem, and an objectof the invention is to provide an information recording medium thatrecords an AV stream in a restricted MPEG-TS format enabling convertingcontent recorded in the MPEG-TS format to the MPEG-PS format, andenables format conversion of seamlessly connected streams whilemaintaining seamless playability. A further object of the invention isto provide an apparatus and a method for recording data on thisinformation recording medium.

Means for Solving the Problems

In a first aspect of the invention, provided is an information recordingmedium for storing video information and audio information encoded intoa system stream together with associated management information.

In the information recording medium, the system stream is allowed tohave a first format (TS) and a second format (PS), the first format (TS)having a packet structure for storing data segmented in packets, thesecond format (PS) having a pack structure for storing data segmented inpacks. The first format (TS) is allowed to have a constrained formatused for converting the system stream from the first format (TS) to thesecond format (PS),

According to the constrained format, a predetermined number of packetsare grouped and managed as a multiplexing unit which corresponds to thepack of the second format, and the system stream is managed in a datamanagement unit (Capsule) which includes a plurality of multiplexingunits. The management information contains playback sequence information(PGC) indicating a playback sequence of the system stream. The playbacksequence information is described by a combination of playback portions(Cells) corresponding to one or a plurality of continuous systemstreams. The management information contains connection information(connection_code) for each playback portion, the connection informationindicating whether each playback portion is played back seamlessly fromthe playback portion in the previous playback sequence. When theconnection information indicates seamless playback, a third systemstream (Bridge-VOB) including a part of each of the two seamlesslyconnected system streams is used to enable seamless playback. The thirdsystem stream is recorded according to the constrained format so thatthe playback time of the video information in the data management unit(Capsule) containing the last packet of the third system stream isgreater than or equal to 0.4 second and less than or equal to 1 second.

In a second aspect of the invention, provided is an informationrecording apparatus for encoding audio information and video informationinto a system stream and recording the system stream with associatedmanagement information to an information recording medium. In theinformation recording apparatus, the system stream is allowed to have afirst format (TS) and a second format (PS), the first format (TS) havinga packet structure for storing data segmented in packets, the secondformat (PS) having a pack structure for storing data segmented in packs.The first format (TS) is allowed to have a constrained format used forconverting the system stream from the first format (TS) to the secondformat (PS). According to the constrained format, a predetermined numberof packets are grouped and managed as a multiplexing unit whichcorresponds to the pack of the second format, and the system stream ismanaged in a data management unit (Capsule) which includes a pluralityof multiplexing units. The management information contains playbacksequence information (PGC) indicating a playback sequence of the systemstream. The playback sequence information is described by a combinationof playback portions (Cells) corresponding to one or a plurality ofcontinuous system streams. The management information containsconnection information (connection_code) for each playback portion. Theconnection information indicating whether each playback portion isplayed back seamlessly from the playback portion in the previousplayback sequence. When the connection information indicates seamlessplayback, a third system stream (Bridge-VOB) including a part of each ofthe two seamlessly connected system streams is used to enable seamlessplayback.

The information recording apparatus includes a first encoding sectionthat applies a specific encoding process to the video information andaudio information to generate a video elementary stream and an audioelementary stream based on the first format (TS); a second encodingsection that applies system-encoding to multiplex the video elementarystream and the audio elementary stream into a system stream based on thefirst format (TS); and a controller that controls the first and secondencoding sections. The controller controls the first and second encodingsections so that the playback time of the video information in the datamanagement unit (Capsule) at the end of the third system stream isgreater than or equal to 0.4 second and less than or equal to 1 second.

In a third aspect of the invention, provided is a method for encodingaudio information and video information into a system stream andrecording the system stream with associated management information to aninformation recording medium. In the method, the system stream isallowed to have a first format (TS) and a second format (PS), the firstformat (TS) having a packet structure for storing data segmented inpackets, the second format (PS) having a pack structure for storing datasegmented in packs. The first format (TS) is allowed to have aconstrained format used for converting the system stream from the firstformat (TS) to the second format (PS). According to the constrainedformat, a predetermined number of packets are grouped and managed as amultiplexing unit which corresponds to the pack of the second format.The system stream is managed in a data management unit (Capsule) whichincludes a plurality of multiplexing units. The management informationcontains playback sequence information (PGC) indicating a playbacksequence of the system stream. The playback sequence information isdescribed by a combination of playback portions (Cells) corresponding toone or a plurality of continuous system streams. The managementinformation contains connection information (connection_code) for eachplayback portion, the connection information indicating whether eachplayback portion is played back seamlessly from the playback portion inthe previous playback sequence. When the connection informationindicates seamless playback, a third system stream (Bridge-VOB)including a part of each of the two seamlessly connected system streamsis used to enable seamless playback.

The information recording method includes applying a specific encodingprocess to the video information and audio information to generate avideo elementary stream and an audio elementary stream based on thefirst format (TS), and multiplexing and system encoding the videoelementary stream and audio elementary stream based on the first format(TS) to generate the system stream. The encoding process is applied sothat the playback time of the video information in the data managementunit (Capsule) at the end of the third system stream is greater than orequal to 0.4 second and less than or equal to 1 second.

EFFECTS OF THE INVENTION

According to the invention, using a restricted encoding method,high-speed conversion from a content multiplexed in MPEG-TS format to acontent multiplexed in MPEG-PS format is achieved. Particularly, whenthe content in MPEG-TS format is edited to be capable of being playedback seamlessly, an edit for seamless can be easily done and seamlessplayback as expected by the edit can be achieved on the content in theconverted MPEG-PS format.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram showing a DVD recording apparatus and anexemplary interface between the DVD recording apparatus and othercomponents used in conjunction therewith.

FIG. 2 is a block diagram of the drive apparatus of a DVD recorder.

FIG. 3A illustrates a contiguous area on the disc, and

FIG. 3B is a graph illustrating the data accumulation in a track buffer.

FIG. 4 is a block diagram of a DVD recorder having a semiconductormemory card and hard disk drive.

FIGS. 5A and 5B show a data region of a disc and data structure of thedisc, respectively.

FIGS. 6A and 6B show the logical data space of the disc.

FIG. 7 shows the disc directory and file structure.

FIG. 8 shows the structure of a video object.

FIG. 9 shows the MPEG system stream.

FIGS. 10A to 10C show the MPEG transport stream (MPEG_TS).

FIGS. 11A to 11C show the MPEG program stream (MPEG_PS).

FIGS. 12A to 12D show a TS packet.

FIGS. 13A to 13C2 shows a PAT table.

FIGS. 14A to 14C show the arrangement of video objects on disc.

FIGS. 15A and 15B show the data structure of video managementinformation.

FIGS. 16A and 16B show the data structure of video managementinformation.

FIG. 17 shows the relationship between an object, object information,and PGC information in the video management information.

FIG. 18 is a block diagram showing the functional configuration of aplayback apparatus.

FIG. 19 is a block diagram showing the functional configuration of arecording apparatus.

FIG. 20 is a block diagram showing the configuration of a data recordingand reproducing apparatus according to the present invention.

FIG. 21 shows the structure of a self-encoding stream.

FIGS. 22A and 22B describes the packet transfer time interval.

FIG. 23 describes a storage method for a User Private packet.

FIG. 24 describes a storage method for a User Private packet.

FIG. 25 describes a storage method for a User Private packet.

FIG. 26 describes a storage method for a User Private packet.

FIGS. 27A to 27H described conversion of an MPEG_TS to an MPEG_PS.

FIGS. 28A to 28G show an encoding method for an MPEG_TS enabling easyconversion to an MPEG_PS.

FIG. 29 shows conversion to a DVD Video format (NTSC).

FIG. 30 shows conversion to a DVD Video format (PAL).

FIG. 31 shows the internal data structure of a User Private packet.

FIG. 32 shows the correlation between an MPEG_TS encoded for easyconversion to an MPEG_PS and the MPEG_PS after conversion.

FIG. 33 is a block diagram of the encoder of a data recording apparatusaccording to the present invention.

FIG. 34 shows differences in processes for converting from aself-encoded MPEG_TS to DVD formats due to differences in systemencoding.

FIG. 35 shows the Tip packet data structure.

FIG. 36 shows the adaptation field data structure.

FIG. 37 shows the Data_ID data structure.

FIG. 38 shows the display_and_copy_info data structure.

FIG. 39 shows the encode_info data structure.

FIG. 40 shows the PES_info data structure.

FIG. 41 shows the MakersPrivateData data structure.

FIG. 42A shows PID of the Tip packet.

FIG. 42B shows the stream_type of Tip packet.

FIG. 43 shows field values of the PES packet header in a ConstrainedSESF stream.

FIG. 44 shows the PES_extension_flag and PES_header_data_length in aConstrained SESF stream.

FIG. 45 shows an example of an MPEG_TS self-encoded such that it doesnot satisfy T_STD model.

FIGS. 46A and 46B show an example of an MPEG_PS converted from a MPEG_TSsuch that the MPEG_PS does not satisfy the P_STD model.

FIG. 47 shows SCR calculation.

FIG. 48 shows the elementary stream attributes of a Constrained SESFwhen encode_condition=11b.

FIG. 49 shows the elementary stream attributes of a Constrained SESFwhen encode_condition=01b.

FIG. 50 shows the stream structure of a format conforming to the DVDVideo standard.

FIG. 51 shows the structure of PCI data in NV_PCK.

FIG. 52 shows the structure of PCI_GI data in NV_PCK.

FIG. 53 shows the structure of DSI data in NV_PCK.

FIG. 54 shows the structure of DSI_GI data in NV_PCK.

FIG. 55 shows the structure of SML_PBI data in NV_PCK.

FIG. 56 shows the structure of SYNCI data in NV_PCK.

FIG. 57 shows the stream structure of a format conforming to the DVDVideo Recording standard.

FIG. 58 is a flow chart of the TS packet (RD_PCK) conversion process.

FIG. 59 is a flow chart of the TS packet (V_PCK, A_PCK) conversionprocess.

FIG. 60 shows a part of the data structure of the pack header in anMPEG-2 program stream pack.

FIG. 61 shows a DVD format system header.

FIG. 62A shows the structure of a packet header stored in RDI_PCK.

FIG. 62B shows the structure of a packet header stored in RDI_PCK.

FIG. 63 shows a part of the data structure of the packet header in anMPEG-2 program stream packet.

FIG. 64 shows the structure of an AC-3 standard private header in theDVD format.

FIGS. 65A and 65B show converting a Constrained SESF to an MPEG_PS for avideo pack.

FIGS. 66A and 66B show converting a Constrained SESF to an MPEG_PS foran audio pack.

FIG. 67 is a table of audio bit rates allowed by the Constrained SESF,and the maximum payload length stored to one audio PES packet for AC-3and MPEG-1 Audio at the corresponding bit rates.

FIG. 68 is a flow chart of overall TS2PS conversion process.

FIG. 69 is a flow chart of initialization process in the TS2PSconversion process.

FIG. 70 is a flow chart of the capsule unit process in the TS2PSconversion process.

FIG. 71 is a flow chart of the pack unit process.

FIG. 72 is a flow chart of the SCR calculation process.

FIG. 73 is a flow chart of the pack header process.

FIG. 74 is a flow chart of the packet header process.

FIG. 75 is a flow chart of the stream ID process.

FIG. 76 is a flow chart of the video PES packet leading process.

FIG. 77 is a flow chart of the video PES packet non-leading process.

FIG. 78 is a flow chart of the audio PES packet leading process.

FIG. 79 is a flow chart of the audio PES packet non-leading process.

FIG. 80 is a flow chart of the payload process.

FIG. 81 is a flow chart of the padding packet process.

FIG. 82 shows the Constrained SESF stream format.

FIG. 83 shows the data structure of an MPEG standard PES packet.

FIG. 84 shows a method of generating NV_PCK data.

FIG. 85 shows efficiency multiplexing method using Multiplexing Unitwith aligned PES packets including audio data.

FIG. 86 shows efficiency multiplexing method using Multiplexing Unitwith aligned PES packets including picture data.

FIG. 87 shows encode conditions related to the order of videopresentation fields in Constrained SESF (encode_condition=11b).

FIG. 88 is a flow chart of recording process for Constrained SESF.

FIG. 89 is a flow chart of the end recording process for ConstrainedSESF.

FIG. 90 describes the structure of a seamlessly connected ConstrainedSESF.

FIG. 91 describes the structure of a seamlessly connected ConstrainedSESF (connection_condition=3)

FIG. 92 describes the structure of a seamlessly connected ConstrainedSESF (connection_condition=3, encode_condition=11b)

FIG. 93 describes the structure of a seamlessly connected ConstrainedSESF (connection_condition=3, encode_condition=01b)

FIG. 94A describes the relationship to audio data at the seamlessconnection in the Blu-Ray Disc (BD) standard, and FIG. 94B describes therelationship to audio data after conversion to one DVD standard VOB.

FIG. 95A describes the relationship to audio data at the seamlessconnection in the Blu-Ray Disc (BD) standard, and FIG. 95B describes therelationship to audio data after conversion to one DVD standard VOB.

FIG. 96 describes the time stamp offset when converting one DVD VOB.

FIG. 97 is a flow chart for converting a seamlessly connectedConstrained SESF to DVD (connection_condition=4).

FIG. 98 is a flow chart for converting a seamlessly connectedConstrained SESF to DVD (connection_condition=3).

FIG. 99 a flow chart continuing the flow chart in FIG. 98 for convertinga seamlessly connected Constrained SESF to DVD.

FIG. 100 a flow chart continuing the flow chart in FIG. 98 forconverting a seamlessly connected Constrained SESF to DVD.

DESCRIPTION OF REFERENCE SIGNS

-   -   100 DVD disk    -   101, 201 optical pickup    -   102, 202 ECC processor    -   103, 203, 220 track buffer    -   104, 210 switch    -   105, 214 encoder    -   106, 205, 206, 218 decoder    -   207 audio decoder    -   208 still picture decoder    -   211 controller    -   212 system controller    -   213 analog broadcast tuner    -   215 digital broadcast tuner    -   216 analyzer    -   217 display unit    -   219 digital I/F    -   221 drive    -   222 user I/F    -   223 line input unit    -   230 User Private packet    -   231 transport stream system target decoder

BEST MODE FOR CARRYING OUT THE INVENTION

A DVD disc, DVD recorder, and DVD player are described with reference tothe accompanying figures in the sequence shown below as preferredembodiments of a data recording medium, recording apparatus, andplayback apparatus according to the present invention.

Key points of the present invention are described particularly in thefollowing section 8, outline of the invention, and section 9, detailedembodiments of the invention. While the relationship to the presentinvention may vary, all of the following describe various aspects of theinvention.

1. Outline of the DVD recorder system

2. Function outline of the DVD recorder

3. Outline of the DVD disc

4. Outline of reproduced AV data

5. AV data management information and playback control

6. Basic operation of the playback function

7. Basic operation of the recording function

8. Detailed embodiments of the invention

The following terminology is used below.

“TS2PS conversion” refers to converting the MPEG transport stream(MPEG_TS) to the MPEG program stream (MPEG_PS).

“DVD format” refers to both the DVD-Video standard format and theDVD-Video Recording standard format, each being an MPEG_PSimplementation.

1. OUTLINE OF THE DVD RECORDER SYSTEM

FIG. 1 shows a typical DVD recorder in relation to other systems anddevices used with the DVD recorder.

As shown in FIG. 1 a DVD, which is a type of optical disc, is loaded tothe DVD recorder for recording video data to the disc and reproducingvideo data from the disc. A remote control device is typically used tooperate the DVD recorder.

The video data input to the DVD recorder could be an analog signal or adigital signal with analog broadcasts exemplary of analog signals anddigital broadcasts exemplary of digital signals. Generally speaking,analog broadcasts are received and demodulated by the receiver built into a television, and input as an NTSC or other analog video signal tothe DVD recorder for recording. Digital broadcasts are demodulated to adigital signal by the digital broadcast receiver (set-top box (STB))input to the DVD recorder for recording.

Video data recorded to a DVD is reproduced by the DVD recorder andexternally output. Like the video input, video output may be an analogsignal or digital signal. Analog signals are input directly to thetelevision. Digital signals are passed through the STB and converted toan analog signal, which is then input to the television for videopresentation.

Video data may also be recorded to and reproduced from a DVD by a deviceother than a DVD recorder, such as a DVD camcorder or personal computer.A DVD disc storing video data recorded by a device other than a DVDrecorder will also be reproduced by the DVD recorder when loadedtherein.

It should be noted that audio data is normally associated with the videodata of an analog broadcast or digital broadcast, and this audio data islikewise recorded and reproduced by the DVD recorder.

Furthermore, the video data is generally moving picture data, but couldalso include still images such as when a still image (photograph) iscaptured using the snapshot function of a DVD camcorder.

IEEE 1394, ATAPI, SCSI, or other standard could be used for the digitalinterface between the STB and DVD recorder.

It should also be noted that an NTSC signal is referred to above as thetype of component video signal passed between the DVD recorder andtelevision, but a component signal sending separate luminance and colordifference signals could be used. Furthermore, changing the interfacefor transmitting video between AV components and televisions from ananalog interface to a digital interface such as DVI is currently beingresearched, and we anticipate that a digital interface can also be usedto connect DVD recorders and televisions.

2. FUNCTION OUTLINE OF THE DVD RECORDER

FIG. 2 is a function block diagram of a DVD recorder. The drive devicehas an optical pickup 101 for reading data from a DVD-RAM disc 100, anECC (error correction code) processor 102, track buffer 103, switch 104for changing track buffer 103 input and output, an encoder 105, and adecoder 106.

As shown in the figure data is recorded to the DVD-RAM disc 100 with thesmallest recording unit being one sector (=2 B). Furthermore, 16 sectorsequal 1 ECC block, and the ECC processor 102 applies error correctionprocessing using ECC block units.

The DVD recorder could also use semiconductor memory cards or hard diskdrives in addition to DVDs as data storage media. FIG. 4 is a blockdiagram of a DVD recorder having a semiconductor memory card and harddisk drive.

It should also be noted that 1 sector could be 512 bytes, 8 KB, or othersize. The ECC block could also contain 1 sector, 16 sectors, 32 sectors,or other configuration. It is expected that the sector size and numberof sectors in each ECC block will also increase as the recordable datacapacity increases.

The track buffer 103 is a buffer for recording AV data at a variable bitrate (VBR) in order to record AV data more efficiently to the DVD-RAMdisc 100. The DVD-RAM disc 100 write rate (Va) is a fixed rate but thebit rate (Vb) of the AV data varies according to the complexity of theAV content (images in the case of video content). The track buffer 103is used to absorb this bit rate difference.

In order to use this track buffer 103 even more effectively, the AV datacan be distributively recorded to the disc 100. This is furtherdescribed with reference to FIGS. 3A and 3B.

FIG. 3A shows the disc address space. As shown in FIG. 3A, continuousplayback of the AV data is enabled when the AV data is recorded toseparate contiguous spaces [a1, a2] and [a3, a4] by supplying dataaccumulated in the track buffer to the decoder 106 while seeking from a2to a3. The change in the amount of data stored to the track buffer atthis time is shown in FIG. 3B.

When reading starts at address a1, the AV data is input from time t1 tothe track buffer 103 and data output from the track buffer 103 alsostarts. Data then accumulates in the track buffer 103 at the rate(Va-Vb), that is, the difference between the input rate (Va) to thetrack buffer 103 and the track buffer output rate (Vb). This continuesuntil the search area reaches a2, that is, until time t2. If the dataaccumulated in the track buffer 103 during this time is B(t2), data canbe supplied to the decoder 106 by gradually depleting the data B(t2)accumulated in the track buffer 103 from time t2 to the time t3 at whichreading from the address a3 begins.

In other words, a continuous supply of AV data can be maintained duringseek operations insofar as at least a specified amount of data ([a1,a2]) has been read before the seek operation starts.

The size of the contiguous area required to enable continuous AV dataoutput when converted to an ECC block count (N_ecc) is shown by thefollowing equation:

N _(—) ecc=Vb*Tj/((N_sec*8*S_size)*(1−Vb/Va))

where N_sec is the number of sectors in an ECC block, S_size is thesector size, and Tj is the seek performance (maximum seek time).

A defective sector could also occur in a contiguous area. The requiredsize of the contiguous area in this case is shown by the followingequation:

N _(—) ecc=dN _(—) ecc+Vb*Tj/((N_sec*8*S_size)*(1−Vb/Va))

where dN_ecc is the size of the allowed defective sector, and Ts is thetime needed to skip the defective sector within the contiguous area.This equation also returns the size of the contiguous area as the numberof ECC blocks.

The above example is described using reading data from a DVD-RAM disc,that is, data playback, by way of example, but it will be obvious thatwriting, that is, recording, data to the DVD-RAM disc can be handled inthe same way.

Continuous data playback and recording can thus be achieved with aDVD-RAM disc even when the AV data is recorded to separate recordingareas on the disc insofar as the data is recorded in blocks of aspecific size or more. These contiguous areas are referred to asContiguous Data Areas (CDA) in DVD terminology.

3. OUTLINE OF THE DVD DISC

FIGS. 5A and 5B show the physical structure and a plan view of aDVD-RAM, i.e., a recordable optical disc. DVD-RAM discs are typicallyhoused in a cartridge for loading to a DVD recorder. The purpose of thecartridge is to protect the disc. The DVD-RAM disc can, however, beloaded directly to the DVD recorder without being housed in a cartridgeif the recording surface can be protected in some other way.

DVD-RAM discs are recorded using a phase-change recording technique.Data on the disc is managed by sector unit, and addresses are added fordata access. Groups of 16 sectors are used for error correction, have anerror correction code added thereto, and are referred to as ECC blocks.

FIG. 5A shows the recording area of a DVD-RAM disc, i.e., a recordableoptical disc. As shown in the figure, a DVD-RAM disc has a lead-in areaat the inside circumference, a lead-out area at the outsidecircumference, and a data area between the lead-in and lead-out areas.

Reference signals for stabilizing the servo when accessing the disc withthe optical pickup, and an ID signal for distinguishing a DVD-RAM discfrom other types of media, are recorded to the lead-in area.

The same reference signals are also recorded to the lead-out area.

The data area is segmented into sectors (each 2048 bytes) as thesmallest access unit. The data area is also segmented into a pluralityof zones in order to apply a rotational control technique known as ZoneConstant Linear Velocity (Z-CLV) during recording and playback.

FIG. 5A shows plural zones formed concentrically on the DVD-RAM disc. Inthis example the DVD-RAM disc is divided into 24 zones, labelled zone 0to zone 23. The rotational angular velocity of the DVD-RAM is setdifferently in each zone such that it increases in proximity to theinside circumference and is constant while the optical pickup accessesdata in the same zone. This increases the recording density of theDVD-RAM and enables easier rotational control during recording andplayback.

FIG. 5B shows the lead-in area, lead-out area, and zones 0 to 23concentrically arranged in FIG. 5A when viewed in a line through thedisc radius.

The lead-in area and lead-out area each include a defect management area(DMA). The defect management area is for recording position informationindicating the location of a sector containing a defect, and substitutesector position information indicating in which substitute area thesector substituted for the defective sector is located.

Each zone includes a user area between a substitute area and an unusedarea. The user area is the area that can be used by the file system as arecording area. The substitute area is the area substitutionally usedwhen there is a defective sector. The unused area is an area not usedfor data recording, and is approximately two tracks wide. The sectoraddress is recorded to the same position in adjacent tracks within eachzone, but with Z-CLV the sector address is recorded to a differentposition in tracks adjacent to the zone boundary. This unused area istherefore provided to prevent sector address detection errors in tracksadjacent to the zone boundary.

There are, therefore, sectors not used for data recording at the zoneboundaries. A logical sector number (LSN) is therefore assigned to eachphysical sector in the user area of a DVD-RAM disc sequentially from theinside circumference in order to continuously identify only thosesectors used for data recording.

FIG. 6 shows the logical data space of a DVD-RAM disc comprising logicalsectors. The logical data space is called the “volume space” and is usedto record user data.

Data recorded in the volume space is managed with a file system. Morespecifically, a group of sectors storing data is a “file,” and volumestructure information managing a group of files as a “directory” isrecorded to the beginning and end of the volume area. The UDF filesystem is used in the present embodiment and conforms to ISO 13346.

The above-noted group of sectors is not necessarily contiguous withinthe volume space, and can be split into separate parts. Of the sectorsconstituting each file, the file system therefore manages each group ofcontiguous sectors in the volume space as an extent, and manages eachfile as a set of related extents.

FIG. 7 shows the structure of a directory and file recorded to DVD-RAM.Below the root is the VIDEO_RT directory, and below VIDEO_RT are thevarious object files containing the playback data and a VIDEO Managerfile containing management information such as the playback sequence andvarious attributes.

Objects are data structures conforming to MPEG standards, and includePS_VOB, TS1_VOB, TS2_VOB, AOB, POB, and MNF (Manufacturer's PrivateData).

PS_VOB, AOB, and POB are MPEG program streams (PS), and TS1_VOB andTS2_VOB are MPEG transport streams (TS). The program stream has a datastructure designed for storing AV data to package media. The transportstream has a data structure intended for communications media.

PS_VOB, TS1_VOB and TS2_VOB are objects of primarily video data butcontaining both video data and audio data. In principle, TS1_VOB objectsare encoded by the DVD recorder with an explicitly managed internalpicture structure. TS2_VOB objects are encoded externally to the DVDrecorder, and part of the internal picture structure and data structureis unknown.

Typically, TS1_VOB objects are externally input analog video signalsencoded by the DVD recorder to the transport stream, and TS2_VOB objectsare externally input digital video signal objects recorded directly todisc without further encoding by the DVD recorder. That is, when a DVDrecorder records digital broadcasting, TS2_VOB is generally used.

AOB and POB are MPEG program streams. AOB objects contain primarilyaudio data, and POB objects contain primarily still images.

The MNF (Manufacturer's Private Data) block is used to store informationspecific to a particular manufacturer.

“Primarily video data” and “primarily audio data” above indicate that ahigh bit rate is allocated. VOB are used in video and similarapplications, and AOB are used in music applications.

4. OUTLINE OF REPRODUCED AV DATA

FIG. 8 shows the structure of MPEG data recorded as AV objects to a DVD.

As shown in FIG. 8, the video stream and audio stream are segmented andmultiplexed. The MPEG standard refers to the multiplexed streams as thesystem stream. In the case of DVD, a system stream containing DVDspecific settings is called a VOB (Video Object). The segmentation unitsare called packs and packets, and are approximately 2 KB in size.

The video stream is encoded according to the MPEG standard, variable bitrate compressed such that the bit rate is increased in complex imagessuch as images containing much movement. The pictures in an MPEG streamare encoded as I-pictures, P-pictures, or B-pictures. I-pictures arespatially compressed and complete within each frame. P-pictures andB-pictures are temporally compressed using inter-frame correlations. Aseries of pictures including at least one I-picture is referred to as aGroup of Pictures (GOP) in MPEG. A GOP is the access point for fast playand other special play modes, which are made possible by the presence ofat least one intra-frame compressed I-picture.

In addition to using MPEG audio, the audio stream of a DVD can beencoded using AC-3, LPCM, or other encoding technique.

As also shown in FIG. 8 the Video Object Unit (VOBU) is the data unitmultiplexing the video data of a GOP with the associated audio data.Video management data can also be included in a VOBU as headerinformation.

A program stream (PS) and transport stream (TS) are included in thesystem stream described with reference to FIG. 8. As noted above, theprogram stream has a data structure intended for package media and thetransport stream data structure is intended for communications media.

FIG. 9 shows the concept of the program stream and transport stream datastructures.

The program stream comprises fixed length packs that are the smallestunit for data transfer and multiplexing. Each pack contains one or morepackets. Both packs and packets comprise a header part and a data part.The data part is referred to as the payload in MPEG. For compatibilitywith the sector size, the fixed length of a pack in DVD is 2 KB. A packcan contain multiple packets, but because packs storing DVD video andaudio contain only one packet, 1 pack equals 1 packet except in specialcases.

The data transfer and units for multiplexing of the transport streamcomprises fixed length TS packets. TS packet size is 188 bytes forcompatibility with ATM transmissions, a communications standard. One ormore TS packets form a PES packet.

PES packets are a concept common to both the program stream andtransport stream, and the data structure is the same. Packets stored inprogram stream packs directly form PES packets, and a group of one ormore transport stream TS packets form a PES packet.

The PES packet is the smallest encoding unit and stores video data andaudio data with common encoding. More specifically, video data and audiodata encoded with different coding methods are not present in a same PESpacket. However, if the coding method is the same, it is not necessaryto ensure the picture boundaries and audio frame boundaries. As shown inFIG. 9 one frame is stored to plural PES packets, and plural frames maybe stored to one PES packet.

FIGS. 10A to 10C and FIGS. 11A to 11C show the data structures of thetransport stream and program stream.

As shown in FIGS. 10A to 10C and FIGS. 12A to 12D, each TS packetcomprises a TS packet header, adaptation field, and payload. The TSpacket header stores a Packet Identifier (PID) whereby the video, audio,or other stream to which the TS packet belongs can be identified.

The Program Clock Reference (PCR) is stored to the adaptation field. ThePCR is the reference value for the system time clock (STC) of the devicedecoding the stream. The device typically demultiplexes the systemstream based on the PCR timing, and then reassembles the video streamand other streams.

The Decoding Time Stamp (DTS) and Presentation Time Stamp (PTS) arestored to the PES header. The DTS indicates the decoding timing of thepicture or audio frame stored to the PES packet, and the PTS indicatesthe presentation timing of the video or audio output.

It should be noted that the PTS and DTS need not be written to every PESpacket header. Decoding and output are possible insofar as the PTS andDTS are written to the header of the PES packet where the first data ofthe I-picture is stored.

The TS packet structure is shown in detail in FIGS. 12A to 12D.

As shown in FIGS. 12A to 12D the adaptation field stores the PCR and arandom access presentation flag. This flag indicates whether data thatis at the beginning of the video or audio frame and can be used as anaccess point is stored in the corresponding payload. In addition to theabove-noted PID, the TS packet header also stores a unit startpresentation flag indicating the beginning of a PES packet, andadaptation field control data indicating whether an adaptation fieldfollows.

FIGS. 11A to 11C show the structure of packs in the program stream. Thepack contains the SCR in the pack header and a stream_id in the packetheader of packets stored in the pack. The SCR is effectively identicalto the transport stream PCR, and the stream_id to the PID. The PESpacket data structure is also the same as in the transport stream, andthe PTS and DTS are stored in the PES header.

One major difference between the program stream and transport stream isthat the transport stream allows for multiple programs. That is, interms of program units, the program stream can carry only one programbut the transport stream can simultaneously transmit multiple programs.This means that the playback device must be able to identify the videostreams and audio streams constituting each program carried in thetransport stream.

FIGS. 13A to 13C2 shows the PAT table and PMAP table used to transmitstructure information for the audio stream and video stream of eachprogram. As shown in FIGS. 13C1 and 13C2 the PMAP table storesinformation relating to the combination of video and audio streams usedin each program, and the PAT table stores information correlatingprograms and PMAP tables. The playback device can therefore referencethe PAT table and PMAP table to detect the video and audio streams forthe program to be output.

How the program stream packs and transport stream TS packets describedabove are arranged on the disc is described next with reference to FIGS.14A to 14C.

As shown in FIG. 14A there are 32 sectors in an ECC block.

As shown in FIG. 14B, the packs (PS Packs) forming a video object(PS_VOB) of a program stream type are located at the sector boundaries.This is because the pack size and sector size are both 2 KB.

Video objects (TS1_VOB, TS2_VOB) of the transport stream type, however,are 8 KB units and are therefore contained in the ECC block. Each 8 KBunit contains an 18 byte header area and 43 TS packets containingArrival Time Stamp (ATS) information in the data area. The ATSinformation is data generated and added by the DVD recorder, andindicates the timing at which the packet was received by the DVDrecorder from an external source.

It should be noted that an MPEG_TS storage format continuously recordingcombinations of fixed-byte length ATS and MPEG_TS packets is alsopossible as shown in FIG. 14C.

5. AV DATA MANAGEMENT INFORMATION AND PLAYBACK CONTROL

FIGS. 15A to 15B and FIGS. 16A to 16B show the data structure of thevideo management information file (Video Manager) shown in FIG. 7.

The video management information includes object information describingsuch management information as where objects are recorded on disc, andpresentation control information describing the playback sequence of theobjects.

FIG. 15A shows an example in which the objects recorded to the discinclude PS_VOB#1-PS_VOB#n, TS1_VOB#1-TS1_VOB#n, and TS2_VOB#1-TS2_VOB#n.

As shown in FIG. 15A a PS_VOB information table, TS1_VOB informationtable, and TS2_VOB information table are separately recorded accordingto the object types. Each of these tables stores VOB information foreach object.

The VOB information includes general information about the correspondingobject, object attribute data, an access map for converting the objectplayback time to a disc address value, and management information forthe access map. The general information includes identificationinformation for the corresponding object and object recording time. Theattributes include video stream attributes (V_ATR) such as the videostream coding mode, the number of audio streams (AST_Ns), and audiostream attributes (A_ATR) such as the audio stream coding mode.

There are two reasons why an access map is required. The first is sothat the playback path information avoids directly referencing objectrecording positions based on a sector address value, for example, andinstead can indirectly reference object locations based on the objectplayback time. Object recording positions can change with RAM media as aresult of editing the object, for example. This increases the amount ofplayback path information that must be updated if the playback pathinformation references object recording positions directly based on thesector address. If the objects are referenced indirectly based on theplayback time, however, it is not necessary to update the playback pathinformation and only the access map needs to be updated.

The second reason is that the audio stream typically has two referencebases, the time base and data (bit stream) base, but the correlationtherebetween is not complete.

For example, using a variable bit rate (a method of changing the bitrate according to the complexity of the image) is becoming the norm withMPEG-2 Video, an international standard for video stream encoding. Inthis case there is no proportional relationship between the amount ofdata from the stream start and playback time, and random access based onthe time base is therefore not possible. An access map is used toresolve this problem by converting between the time base and data (bitstream) base.

As shown in FIG. 15A, the presentation control information includes auser-defined playback path information table, original playback pathinformation table, and title search pointer.

As shown in FIG. 16A there are two types of playback paths data:originally defined playback path information generated automatically bythe DVD recorder to describe all objects recorded during objectrecording, and user-defined playback path information enabling a user tofreely define a particular playback sequence. The playback pathinformation is uniformly referred to as Program Chain Information (PGCinformation) on a DVD, the user-defined playback path information isreferred to as the U_PGC information, and the original playback pathinformation as the O_PGC information. The U_PGC information and O_PGCinformation are tables listing the cell information describing the cellsin the object playback period. The object playback period indicated bythe O_PGC information is called an original cell (O_CELL), and theobject playback period indicated by the U_PGC information is called auser cell (U_CELL).

A cell indicates the object playback period using the object playbackstart time and playback end time; the playback start and end times areconverting by the access map described above to the actual locationwhere the object is recorded on disc.

As shown in FIG. 16B, a cell group indicated by the PGC informationdefines a continuous playback sequence reproduced sequentially accordingto the order of entries in the table.

FIG. 17 shows a specific relationship between objects, cells, PGC, andaccess map.

As shown in FIG. 17 the original PGC information 50 contains at leastone cell information entry 60, 61, 62, 63.

Each cell information entry defines the object to reproduce as well asthe object type, and object playback period. The order of the cellinformation entries in the PGC information 50 defines the playbacksequence of the objects defined by each cell when the objects arereproduced.

Each cell information entry (cell information 60, for example) includesa Type 60 a indicating the type of specific object, an Object ID 60 bidentifying a particular object, and a start presentation time Start_PTM60 c and end presentation time End_PTM 60 d in the object on the timebase.

During data playback the cell information 60 is sequentially read fromthe PGC information 50, and the objects specified by each cell arereproduced for the playback period defined by the cell.

The access map 80 c converts the start and end time informationcontained in the cell information to the object address on disc.

This access map is the map information described above and is generatedand recorded when the objects are recorded. The picture structure of theobject data must be analyzed in order to generate the map. Morespecifically, it is necessary to detect the I-picture location shown inFIG. 9, and detect the PTS and other time stamp information, that is,the I-picture playback time shown in FIGS. 10A to 10C and FIGS. 11A to11C.

Problems occurring when generating the PS_VOB, TS1_VOB, and TS2_VOB mapinformation are described next.

As described with reference to FIG. 1, the PS_VOB and TS1_VOB areprimarily generated by the DVD recorder encoding a received analogbroadcast to an MPEG stream. The I-picture and time stamp information istherefore auto-generated by the DVD recorder, the internal datastructure of the stream is known to the DVD recorder, and the mapinformation can be generated with no problem.

As also described with reference to FIG. 1, the TS2_VOB is a receiveddigital broadcast recorded directly to disc by the DVD recorder with nointermediate encoding. Because the recorder thus does not generate thetime stamp information and determine the I-picture locations as it doeswhen recording a PS_VOB, the DVD recorder does not know the internaldata structure of the stream and must therefore detect this informationfrom the recorded digital stream.

To do this the DVD recorder detects the I-picture and time stampinformation for the map information of a TS2_VOB recording a streamencoded externally to the recorder as follows.

First, I-pictures are detected by detecting the random accesspresentation information of the TS packet adaptation field shown inFIGS. 12A to 12D. The time stamp information is detected by detectingthe PTS in the PES header. Note that the PCR from the adaptation fieldor the ATS indicating the TS packet arrival time at the DVD recorder canbe used instead of the PTS for the time stamp. In any case, the DVDrecorder detects I-picture locations based on information in a highlevel system layer and does not need to analyze the data structure ofthe MPEG stream video layer. This is because the system overheadrequired to analyze the video layer in order to generate the mapinformation is great.

There are also cases in which system layer detection is not possible.The map information cannot be generated in such cases and it istherefore necessary to indicate that there is no valid map information.The DVD recorder indicates this using the map management informationshown in FIG. 15B.

The map management information shown in FIG. 15B contains map validityinformation and a self-encoding flag. The self-encoding flag indicatesthat an object was encoded by the DVD recorder, and thus indicates thatthe internal picture structure is known and that the map informationtime stamp information and I-picture location information is accurate.The map validity information indicates whether or not there is a validaccess map.

Examples of when the system layer cannot be detected include when theadaptation field is not set and when the digital stream is not an MPEGtransport stream. Various digital broadcasting standards and formats areused around the world, and there will naturally be cases in which theDVD recorder records objects for which it cannot generate a map. Forexample, if a DVD recorder designed for the Japanese market andrecording digital broadcasts in Japan is used in the United States torecord digital broadcasts in the United States, there will likely becases in which the DVD recorder cannot generate a map for the recordedobjects.

The DVD recorder can, however, sequentially reproduce from the beginningobjects for which map information is not generated. In this case videofrom the recorded digital stream can be reproduced by outputting itthrough a digital interface to a STB appropriate to the stream.

6. BASIC OPERATION OF THE PLAYBACK FUNCTION

The playback operation of a DVD recorder/player for reproducing contentrecorded to an optical disc as described above is described next belowwith reference to FIG. 18.

As shown in FIG. 18 the DVD player has an optical pickup 201 for readingdata from the optical disc 100, an ECC processor 202 for errorcorrection processing of the read data, a track buffer 203 fortemporarily storing the read data after error correction, a PS decoder205 for reproducing video objects (PS_VOB) and other program streams, aTS decoder 206 for reproducing digital broadcast objects (TS2_VOB) andother transport streams, an audio decoder 207 for reproducing audioobjects (AOB), a still picture decoder 208 for decoding still pictureobjects (POB), a switching means 210 for changing data input to thedecoders 205 to 208, and a controller 211 for controlling the variousparts of the player.

Data recorded to the optical disc 100 is read by the optical pickup 201,passed through the ECC processor 202 and stored to track buffer 203.Data stored to the track buffer 203 is then input to and decoded andoutput by the PS decoder 205, TS decoder 206, audio decoder 207, orstill picture decoder 208.

The controller 211 determines what data to be read based on the playbacksequence defined by the playback path information (PGC) shown in FIGS.16A and 16B. Using the example shown in FIGS. 16A and 16B, thecontroller 211 thus first reproduces part (CELL #1) of VOB #1, then part(CELL #2) of VOB #3, and finally VOB #2 (CELL #3).

Using the cell information of the playback path information (PGC) shownin FIG. 17, the controller 211 an also capture the type of cellreproduced, corresponding objects, and the playback start and end timesof the objects. The controller 211 inputs the data for the period of theobject specified by the cell information to the appropriate decoder.

The controller 211 also identifies the objects to be reproduced based onthe Object ID of the cell information. The controller 211 alsoidentifies the a cell, which is the playback period of the identifiedobject, by converting the Start_PTM and End_PTM of the cell informationto a disc address value by referencing the access map of thecorresponding VOB information.

A player according to this embodiment of the invention also has adigital interface 204 for supplying the AV stream to an external device.It is therefore possible to supply the AV stream to an external devicethrough an IEEE 1394, IEC 958, or other communications means. This is sothat, for example, when the player does not have an internal decoder fordecoding a TS2_VOB not encoded by the recorder/player the TS2_VOB can beoutput directly without decoding through the digital interface 204 to anexternal STB for decoding and presentation via the STB.

When the digital data is directly output to an external device, thecontroller 211 determines whether random access playback is possiblebased on the map information shown in FIG. 15B. If the access point dataflag (random access presentation flag) is valid, the access map containsI-picture location information. In this case the controller 211 is ableto access and output digital data containing an I-picture to an externaldevice through the digital interface in response to fast play and otherrequests from the external device. Furthermore, time-base access is alsopossible if the time access information flag is valid. In this case thecontroller 211 can access and output digital data including the picturedata at a specified playback time to an external device through thedigital interface in response to a time-base access request from anexternal device.

7. BASIC OPERATION OF THE RECORDING FUNCTION

The configuration and operation of a DVD recorder according to thepresent invention for recording and reproducing an optical disc asdescribed above is described next below with reference to FIG. 19.

As shown in FIG. 19 the DVD recorder has a user interface 222 forreceiving user requests and displaying information and prompts to theuser, a system controller 212 handling the overall management andcontrol of the DVD recorder, an analog broadcast tuner 213 for receivingVHF and UHF broadcasts, an encoder 214 for converting analog signals todigital signals and encoding the digital signals to an MPEG programstream, a digital broadcast tuner 215 for receiving digital satellitebroadcasts, an analyzer 216 for interpreting the MPEG transport streamsent from a digital satellite, a display unit 217 such as a televisionand speakers, and a decoder 218 for decoding the AV stream. The decoder218 has first and second decoders, for example, such as shown in FIG.18. The DVD recorder also has a digital interface 219, track buffer 220for temporarily storing write data, and a drive 221 for writing data tothe disc. The digital interface 219 is an IEEE 1394 or othercommunications interface for outputting data to an external device.

With a DVD recorder thus comprised the user interface 222 first receivesa request from the user. The user interface 222 then passes the requestto the system controller 212, and the system controller 212 interpretsthe user request and instructs the various modules to run appropriateprocesses.

Recording includes self-encoding in which the DVD recorder encodes theinput digital data, and outside encoding for recording already encodeddigital data to disc without further encoding.

7.1 Recording Operation by Self-Encoding Recording with self-encoding isdescribed specifically first below using by way of example encoding andrecording an analog broadcast to a PS_VOB stream.

The system controller 212 sends a receive command to the analogbroadcast tuner 213 and an encode command to the encoder 214.

The encoder 214 then video encodes, audio encodes, and system encodesthe AV data from the analog broadcast tuner 213, and passes the encodeddata to the track buffer 220.

Immediately after encoding starts, the encoder 214 sends the time stampinformation at the beginning of the MPEG program stream being encoded tothe system controller 212 as the playback start time (PS_VOB_V_S_PTM),and parallel to the encoding process sends the data required to createthe access map to the system controller 212. This value is set as theStart_PTM of the cell information shown in FIG. 17 and generated later.The time stamp information is generally the PTS, but the SCR can be usedinstead.

The system controller 212 then sends a record command to the drive 221,and the drive 221 thus extracts and records data accumulated in thetrack buffer 220 to the DVD-RAM disc 100. A contiguous data area (CDA)as described above is also found in the recordable area of the disc andthe data is recorded to the located contiguous data area.

Recording typically ends when the user inputs a stop recording command.Stop recording commands from the user are input through the userinterface 222 to the system controller 212, and the system controller212 then sends a stop command to the analog broadcast tuner 213 andencoder 214.

The encoder 214 stops encoding when it receives the stop encodingcommand from the system controller 212, and sends the time stampinformation of the last data in the last encoded MPEG program stream tothe system controller 212 as the playback end time (PS_VOB_V_E_PTM).This value is set as the End_PTM of the cell information shown in FIG.17. The PTS is normally used for the time stamp information but the SCRcan be used instead.

After ending the encoding process the system controller 212 generatesthe presentation control information and VOB information (PS_VOBI) forthe PS_VOB shown in FIGS. 15A and 15B.

The VOB information generated here includes map management informationand an access map appropriate to the object type. The system controller212 sets the map validity information of the map management informationto “valid,” and sets the self-encoding flag ON.

Original playback information (O_PGC information) as shown in FIG. 16Afor the recorded object as one of the playback objects is generated asthe presentation control information. This O_PGC information is added tothe original playback path table. The original playback path (O_PGCinformation) contains cell information. The cell information Type is setto PS_VOB.

The system controller 212 then instructs the drive 221 to stop recordingdata accumulated in the track buffer 220 and to record the PS_VOB VOBinformation (PS_VOBI) and presentation control information. The drive221 thus records the remaining data in the track buffer 220 and thisinformation to the optical disc 100, and the recording process ends.

It will be obvious that an analog broadcast could be encoded to TS1_VOB.In this case the encoder 214 must be an encoder for converting theanalog signal to a digital signal and encoding the digital signal to theMPEG transport stream, and the cell information Type is set to TS1_VOB.

The PTS or PCR can be used for the Start_PTM and End_PTM.

7.2 Recording Operation by Outside Encoding

Recording with outside encoding is described specifically next belowwith reference to recording a digital broadcast. The recorded objecttype in this case is TS2_VOB.

A digital broadcast recording request from the user is passed from theuser interface 222 to the system controller 212. The system controller212 then instructs the digital broadcast tuner 215 to receive andinstructs the analyzer 216 to interpret the received data.

An MPEG transport stream sent from the digital broadcast tuner 215 ispassed through the analyzer 216 to the track buffer 220.

To generate the VOB information (TS2_VOBI) of the encoded MPEG transportstream (TS2_VOB) received as a digital broadcast, the analyzer 216 firstextracts the time stamp information at the beginning of the transportstream as the start time information (TS2_VOB_V_S_PTM) and sends it tothe system controller 212. This start time value is set as the Start_PTMof the cell information shown in FIG. 17 and generated later. The timestamp information is the PCR or PTS. The ATS indicating the timing atwhich the object is sent to the DVD recorder could alternatively beused.

The analyzer 216 then analyzes the system layer of the MPEG transportstream to detect the information needed for access map generation. TheI-picture locations in the object are detected based on the randomaccess indicator (random_access_indicator) in the adaptation field ofthe TS packet header as described above.

The system controller 212 then outputs a record command to the drive221, and the drive 221 thus extracts and records data accumulated in thetrack buffer 220 to the DVD-RAM disc 100. The system controller 212 alsoinstructs the drive 221 where to record on the disc based on theallocation data of the file system. A contiguous data area (CDA) asdescribed above is also found in the recordable area of the disc and thedata is recorded to the located contiguous data area.

Recording typically ends when the user inputs a stop recording command.Stop recording commands from the user are input through the userinterface 222 to the system controller 212, and the system controller212 then sends a stop command to the digital broadcast tuner 215 andanalyzer 216.

In response to the received stop command from the system controller 212,the analyzer 216 stops interpreting the received data and sends the timestamp information at the end of the last interpreted MPEG transportstream to the system controller 212 as the playback end time(TS2_VOB_V_E_PTM). This value is set as the End_PTM of the cellinformation shown in FIG. 17. The PCR or PTS is used for the time stampinformation but the ATS indicating the time when the object was sent tothe DVD recorder can be used instead.

After ending the digital broadcast reception process, the systemcontroller 212 generates the presentation control information and VOBinformation (TS2_VOBI) for the TS2_VOB as shown in FIGS. 15A and 15Bbased on the information received from the analyzer 216.

The VOB information generated here includes map management informationand an access map appropriate to the object type. The system controller212 sets the map validity information of the map management informationto “valid” if the I-picture locations in the objects were detected andthe access map could be generated. The self-encoding flag is set OFF. Ifa valid access map could not be generated the map validity informationis set to an “invalid” state. Examples of when a valid access map cannotbe generated include when a corresponding digital broadcast is notreceived and when there is no random access data set in the adaptationfield. If the signal is input directly through the digital interface thesignal may also not be an MPEG transport stream, and in this case, too,the map validity flag is set to “invalid.”

Original playback information (O_PGC information) as shown in FIGS. 16Aand 16B for the recorded object as one of the playback objects isgenerated as the presentation control information. This O_PGCinformation is added to the original playback path table. The originalplayback path (O_PGC information) contains cell information. The cellinformation Type is set to TS2_VOB.

The system controller 212 then instructs the drive 221 to stop recordingdata accumulated in the track buffer 220 and to record the TS2_VOB VOBinformation (TS2_VOBI) and presentation control information. The drive221 thus records the remaining data in the track buffer 220 and thisinformation to the optical disc 100, and the recording process ends.

While the above recording operations are described with reference touser-input recording start and end commands, it will be obvious that thesame essential operation applies to timer recordings controlled by aVCR, for example. In this case the system controller automaticallyissues the recording start and end commands instead of the user, andthere is no essential change in DVD recorder operation.

8. DETAILED EMBODIMENTS OF THE INVENTION First Embodiment

The basic recording and playback operations of a data recording andreproducing apparatus according to the present invention aresubstantially as described above, and only the basic operation forrecording analog line input is therefore described specifically belowwith reference to FIG. 20. The recorded object type in this case isTS1_VOB.

Analog line input recording requests from a user are passed from theuser interface 222 to the system controller 212. The system controller212 then sends a receive command to the line input unit 223 and a dataencoding command to the encoder 214.

The MPEG transport stream from the encoder 214 is sent to the trackbuffer 220.

To generate the VOB information (TS1_VOBI) of the encoded MPEG transportstream (TS1_VOB), the encoder 214 first sets the time stamp informationas the presentation start time (TS1_VOB_V_S_PTM) and sends it to thesystem controller 212. This start time value is set as the Start_PTM ofthe cell information generated later and shown in FIG. 17. The timestamp information is the PCR or PTS.

The encoder 214 also generates the data needed for access map generationwhile generating the MPEG transport stream. This is done by, forexample, storing the adaptation field in the first MPEG transport packetof the I-picture, setting the random_access_indicator bit, and notifyingthe system controller 212 of the start of a VOBU.

The system controller 212 then sends a record command to the drive 221,and the drive 221 extracts and records data from the track buffer 220 tothe DVD-RAM disc 100. The system controller 212 also instructs the drive221 where to record on the disc based on the allocation data of the filesystem. A contiguous data area (CDA) as described above is also found inthe recordable area of the disc and the data is recorded to the locatedcontiguous data area.

Recording typically ends when the user inputs a stop recording command.Stop recording commands from the user are input through the userinterface 222 to the system controller 212, and the system controller212 then sends a stop command to the encoder 214.

In response to the received stop command from the system controller 212,the encoder 214 stops the encoding process and sends the time stampinformation included in data at the end of the last encoded MPEGtransport stream to the system controller 212 as the end presentationtime (TS1_VOB_V_E_PTM). This value is set as the End_PTM of the cellinformation shown in FIG. 17. The time stamp information becomes PCR orPTS.

After ending the recording process, the system controller 212 generatesthe playback control information and VOB information (TS1_VOBI) for theTS1_VOB as shown in FIGS. 15A and 15B based on the information receivedfrom the encoder 214.

The VOB information generated here includes an access map and mapmanagement information those adapted to the object type. The systemcontroller 212 sets the map validity information of the map managementinformation to “valid”. The self-encoding flag is set ON.

Original playback path information (O_PGC information) as shown in FIGS.16A and 16B for the recorded object as one of the playback objects isgenerated as the presentation control information. This O_PGCinformation is added to the original playback path table. The originalplayback path information (O_PGC information) contains cell information.Type information of the cell information is set to “TS1_VOB”.

The system controller 212 then instructs the drive 221 to stop recordingdata accumulated in the track buffer 220 and to record the VOBinformation (TS1_VOBI) and playback control information for TS1_VOB. Thedrive 221 thus records the remaining data in the track buffer 220 andthis information to the optical disc 100, and the recording processends.

The self-encoding MPEG transport stream generated by the encoder 214 isdescribed in further detail below.

The structure of the self-encoding MPEG transport stream is shown inFIGS. 21A and 21B. As shown in the figure the self-encoding MPEGtransport stream is segmented into VOBU units. Each VOBU starts with aPAT packet, PMT packet, and a User Private packet (UP packet) embeddedwith stream-specific data. A PAT packet and PMT packet at least are alsolocated at the beginning of the VOB.

As shown in FIG. 21B an ATS indicating the decoder input time is alsoadded to each packet, and each packet is input to the decoder at thetime intended by the ATS.

The self-encoding program information (such as the PMT packet PID) isstored to the PAT packet of the first packet and input to the decoder atthe time indicated by ATS1.

The PID for each elementary stream composing the program is stored tothe PMT packet of the second packet. In this example PIDs for the video,audio, data broadcast (“Data” in the figure), and user private(“private” in the figure) packets are stored.

Information added to the stream is stored to the user private packet inthe third packet. This added information could, for example, include:stream title information; recording date and time information; streamattributes, that is, stream encoding information such as the bit rate,video resolution, frame rate, aspect ratio, or encoding method; inputsource identification information for identifying whether the line inputis analog or digital; information indicating the AV data encoding methodif the data is digital; copyright protection information indicatingwhether copying is allowed or prohibited; Vertical Blanking Interval(VBI) signals such as closed caption (CC) data, teletext data, orWide_Screen Signaling (WSS) data used for display control; informationindicating system encoding conditions; DVD standard compatibilityinformation; menu information provided for user convenience usingspecific data provided by the manufacturer that recorded the stream; anddata useful for conversion to various DVD standard MPEG program streams(MPEG_PS).

The decoder input time for a packet stored in this added information andlocated in the MPEG transport stream as above is described next withreference to FIGS. 22A and 22B.

FIG. 22A is a block diagram showing the basic configuration of a decoderreferred to as a transport stream system target decoder (T_STD). Thisfigure further shows a system decoder 235 for interpreting a PSI packetand providing decoder control (not described above).

When a PAT (PSI packet), or PMT packet, as PSI packet, is input to theT_STD, the packet is discriminated according to packet type bydemultiplexer 232, and the PSI packet which is used for system controlis sent immediately to a transport buffer 233.

Data accumulated in the transport buffer 233 is then streamed to thesystem buffer 234 at a rate of 1,000,000 bits/second (=Rsys).

The PSI data becomes valid the moment the required PSI data isaccumulated in the system buffer 234.

This T_STD model in MPEG thus defines an operating model for the decoderand defines standards for the MPEG transport stream transfer rate, forexample.

There are several restrictions on PSI packet transfer because the datarecording apparatus must self-encode the transport stream according toan MPEG transport stream format that assures the T_STD can correctlydecode the transport stream. A method of determining the ATS thatdetermines the packet transfer rate is described next with reference toFIG. 22B.

When reproducing a self-encoding stream the leading PAT, PMT, and UPpackets are input to the T_STD at the time indicated by ATS1, ATS2, andATS3, respectively.

The PMT packet and UP packet are now considered, in order to interpret,by the T_STD, the PID of the UP packet specified by the PMT packet andvalid it, the last byte (byte m) of the TS_program_map_section must bestored in the system buffer 234.

That is, for the PMT to be valid (m+n+5)×8/Rsys seconds must have passedfrom ATS2 as the PMT packet input time. Note that n is the byte lengthof the PMT packet adaptation_field.

Because the System Clock Frequency (SCF) as the T_STD reference clock is27,000,000 Hz (with a defined tolerance range of 810 Hz for error), thefollowing relationship between ATS3 and ATS2 must be true if the ATS isa time expressed to the precision of the System Clock Frequency.

ATS3≧ATS2+((m+n+5)*8/Rsys)*SCF

Because the shortest interval between ATS2 and ATS3 is only when thereis no adaptation_field (n=0) in the PMT packet and the smallestTS_program_map_section (21 bytes) is stored in the PMT packet, a timeinterval of 208/Rsys×SCF is shortest.

The following relationship is likewise required for the input time ATS1of the PAT packet and input time ATS2 of the PMT packet

ATS2≧ATS1+((m0+n0+5)*8/Rsys)*SCF

where m0 is the byte length of the Program association section in thePAT packet, and n0 is the byte length of the adaptation_field in the PATpacket.

Furthermore, because the shortest interval between ATS1 and ATS2 is onlywhen there is no adaptation_field (n=0) in the PAT packet and thesmallest Program association section (16 bytes) is stored to the PATpacket, a time interval of 168/Rsys×SCF is shortest.

If time is expressed with a precision of 27 MHz using a System ClockFrequency (SCF) of 27 MHz, the shortest time interval between ATS1 andATS2 and between ATS2 and ATS3 is 4536 and 5616, respectively.

Storing the User Private packet to the self-encoding transport stream isdescribed next with reference to FIGS. 23 to 26.

FIG. 23 shows storing the UP packet when the UP packet is defined as aUser Private stream. In this case an identification number greater thanor equal to “0x80” and less than or equal to “0×FF” is allocated tostream_type of the PMT corresponding to the UP packet. A unique PID isassigned to the UP packet. The internal data structure of the UP packetdoes not conform to the MPEG standard. Note that in this example the UPpacket includes a section structure called the DVD_attribute_section( ).

FIG. 24 shows a further storage method whereby a private_sectionstructure is included in the UP packet and a unique PID is assigned. Thedata structure of the private_section will vary somewhat according tothe value of the section_syntax_indicator in the private_section, butdata specific to the UP packet is stored in the private_data_byte of theprivate_section. In this case, identification number of 0x00 is assignedto stream_type.

FIG. 25 shows a method of storing a UP packet as a packet with the samePID as the PMT packet. In this case the UP packet data structureconforms to the private_section structure. The stream type is notdefined, and PID of PMT packet is assigned to UP packet.

FIG. 26 shows an example in which the UP packet is not stored separatelybut is enclosed in the PMT packet. In this case the specific dataequivalent to the UP packet has a private_section structure, and theprivate_section is written after the TS_program map_section. That is,PMT packet includes both TS_program map_section and private_section.

The specific data stored to the MPEG_TS by the above-noted methods isdescribed next.

As shown in FIGS. 23 to 26, this specific data includes the Real-timeData Information General Information (RDI_GI) of the RDI Unit and theDisplay Control Information and Copy Control Information (DCI_CCI) ofthe DVD Video Recording standard.

The RDI_GI stores the first presentation start time (VOBU_S_PMT) of theVOBU and the recording date and time information. The DCI_CCI stores,for example, the VOBU aspect ratio information, subtitle modeinformation, film or camera mode information and other informationrelated to display control, copy generation management information, APSinformation, and input source information. (For further informationabout RDI_GI and DCI_CCI, see the DVD Video Recording standard.)

The V_ATR field stores the video bit rate, resolution, frame rate (orvideo_format such as NTSC or PAL), aspect ratio, and encoding method (anMPEG2 Video or MPEG1_Video identifier).

Likewise, the A_ATR field stores the bit rate for all or part of theaudio, encoding method, channel count, quantization bits, and dynamicrange control information according to the number of audio streams.

The CC field stores the closed caption data for the VOBU. To improve thetransferability of PS conversion, closed caption data can be written inan extension_and_user_data (1) format (a method of storing user data tothe GOP layer), or the closed caption data could be written separately.

Storing the closed caption data to the user data of the GOP layerimproves MPEG_PS conversion efficiency because the DVD Video and DVDVideo Recording standards are defined for this purpose.

The C_SE field stores information relating to some problems associatedwith TS2PS conversion of the VOBU or VOB.

Regarding the CC, WSS, or teletext data storage location information,that information indicates whether, for example, closed caption data iscontained in the UP packet, whether closed caption data is written asuser data to the picture headers, or whether there is no closed captiondata in the particular VOBU (or VOB).

Regarding the WSS storage location information, that information furtherindicates whether it is stored as specific data in the UP packet, orwhether it is written to the user data in the picture headers.

Regarding the teletext storage location information, it indicateswhether a TS packet is provided for storing the teletext data, orwhether it is written to the user data in the picture headers.

Regarding the multiplexed block structure and transfer information, thatinformation includes information indicating if the number of TS packetsin the multiplex block (a data block in which only one elementary streamis stored without being mixed with another elementary stream) as shownin FIGS. 27A to 27H is fixed or variable, the number of packets if thenumber is fixed, information indicating whether a PTS/DTS is added tothe first TS packet in the multiplex block, or the transfer rate withinthe same multiplex block. During MPEG_TS encoding imposing no conditionson conventional multiplexing, the multiplex block can be written with afixed length including only one TS packet.

The decoder buffer control information includes vbv_delay, a parameterof the video verifying buffer, information such as vbv_buffer_sizeindicating the remaining video buffer capacity (this information is usedto determine how far ahead of the ATS input time the video data can beread), and the time difference between the decoding time and the inputcompletion time of the VOBU frame for which the buffer input time isclosest to the frame decoding time (this information is used todetermine how far back from the ATS input time the video or audio datacan be read).

The DVD_Compatibility information indicates the overhead involved withsystem transcoding a MPEG_TS to a MPEG_PS conforming to a DVD standard.

The DVD_Compatibility information indicates how easy it is to convert aMPEG_TS to other DVD formats. For example, if the multiplex blocks are 2KB or less, a level 1 indicator is set; if there is closed caption, WSS,or teletext data, the closed caption or WSS data is stored to an UPpacket, and the teletext data is stored as a teletext packet in amultiplex block storing video data, a level 2 indicator is set; if it isnot necessary to consider buffer management when the closed caption,WSS, or teletext data is stored to the area specified by the DVDstandard, a level 3 indicator is set; and if it is not necessary toconsider buffer management when the ATS of the first TS packet in themultiplex block is replaced by the SCR, a level 4 indicator is set.

This DVD_Compatibility information is thus a data set indicating theease of convertibility to various DVD formats, including DVD Video, DVDAudio, DVD Video Recording, and DVD Stream Recording.

FIGS. 27A to 27H show the structure of an MPEG_TS using multiplexblocks, and the data structure when this MPEG_TS is converted to DVDVideo and DVD Video Recording formats.

The self-encoded TS stream shown in FIG. 27A comprises the VOBU(playback and decoding units) of the self-encoded TS stream shown inFIG. 27B. As shown in FIG. 27C one VOBU includes multiple multiplexblocks (corresponding to MPEG_PS packs). Each multiplex block can besegmented into fixed length data units as shown in FIG. 27D (enablingeasy packaging in the device) or into variable length data units asshown in FIG. 27E (thereby consuming less disc space). In the casesshown in FIGS. 27D and 27E the multiplex blocks are respectively formedby segmenting non-elementary steams such as PSI/SI packets or UP packetsand the elementary stream, but as shown in FIG. 27F a multiplex blockcould store both an elementary stream and non-elementary stream objectssuch as PSI/SI packets or UP packets. Note that in FIG. 27F multiplexblock #1 and multiplex block #2 are one multiplex block.

The above streams can be easily converted to the DVD Video format shownin FIG. 27G or the DVD Video Recording format shown in FIG. 27H.

In this case it is important for simple TS2PS conversion that theMPEG_PS packs are formed in the multiplex block sequence and onemultiplex block is the unit storing one pack of data.

It should be noted that the capsule header and ATS are only looselyrelated to the present invention and are therefore omitted in FIGS. 27Ato 27H. In addition, the packs in the converted MPEG_PS shown in FIGS.27G and 27H are also stuffed or padded as appropriate according to thebyte length and VOBU alignment of the stored elementary.

FIGS. 28A to 28G describes the multiplexing method of the presentinvention, comparing with the conventional stream multiplexing methodshown in FIG. 8. As shown in the figure the final format conforms to theMPEG_TS format shown in FIG. 28G. The video stream (FIG. 28A) comprisesplural GOP (FIG. 28B). Each GOP contains specific picture data, and a TSpacket group of a data size equivalent to the data size of one pack whenconverted to an MPEG_PS is one multiplex block (FIG. 28C). That is, onemultiplex block is segmented into plural TS packets equivalent to thedata size of one pack as shown in FIG. 28D. The audio stream is likewisepacked in one multiplex block group having a plurality of TS packets. Assown in FIG. 28E, a VOBU is formed by multiplexing by multiplex blockunit. The greatest difference between the present invention and theprior art shown in FIG. 8 is in that data units of a size equivalent tothe data size of one MPEG_PS pack are grouped to form the multiplexblocks (see FIG. 28E).

Furthermore, the ATS may be added to each MPEG_TS packet while increasedby a specific amount (ΔATS) in each packet within the same multiplexblock as shown in FIG. 29. This is effective to avoid complex buffermanagement during TS2PS conversion, and convert ATS to SCR using asimple offset or no offset. ATSi (i=0, 1, 2 . . . ) in this casesatisfies the following equation.

ATSi+(packet count in the multiplex block)×ΔATS≧ATSi+1

When the multiplex block is a fixed length, the number of TS packets inone multiplex block is fixed and thus the multiplex block boundaries areeasily known. However, when the multiplex block is variable length, thenumber of TS packets in one multiplex block is also variable and thusthe multiplex block boundaries are not easily known. Therefore, theincrease (ΔATS) in the ATS at the multiplex block boundary is set to aspecific value different from the (constant) increase within themultiplex block. That is, the difference (ΔATS) between the ATS of thelast packet in the previous multiplex block and the ATS of the firstpacket in the immediately following multiplex block is set to a specificvalue which is not the constant value. This makes it possible to knowthe multiplex block boundaries by monitoring ΔATS. A 1:1 correlationbetween packs and TS packets when converting to an MPEG_PS can thereforebe assured. ATSi in this case satisfies the following equation.

ATSi+(packet count in the multiplex block)×ΔATS<ATSi+1

Furthermore, the ATSi added to the first packet in the MPEG_TS multiplexblock corresponds to SCRi added to each pack in the MPEG_PS afterconversion.

Furthermore, as also shown in FIG. 29, closed caption, DSI, or othertext information can also be stored in the UP packet. The DSI in the UPpacket is used to generate NV_PCK data after conversion, and the closedcaption data is stored to the video pack. To enable compatibility withthe PAL standard used in Europe, packets storing teletext data in themultiplex block can be inserted between the video data packets as shownin FIG. 30. In this case the teletext data packets are locatedimmediately before the simultaneously presented picture having the samePTS. After conversion the teletext data is stored to the video pack.

FIG. 31 shows the data structure of a UP packet storing the DSI asdescribed above.

Information (such as a relative number from the beginning of the VOBU)identifying the TS packet storing the last byte of the first I-picturein the VOBU can also be described in the added information of the UPpacket to enable efficient special playback modes. Special playbackmodes can also be supported by also describing picture encoding typeinformation of some of I- and P-pictures or all pictures in the VOBU,the data size of each picture (such as information identifying the TSpacket containing the last byte), and information indicative of theDTS/PTS for each picture.

It should be noted that if encoding is done so that TS packet containingthe PTS/DTS is located at the beginning of the multiplex block in thepresent embodiment, the beginning of an access unit will be located atthe beginning of the packs after TS2PS conversion, and simplifiedDVD-specific header processing can be expected.

To prevent an overflow of data stored to MPEG_PS packs and easeconversion to an MPEG_PS, the TS packets of the multiplex blocks can beappropriately stuffed or a necessary number of stuffing bytes can beinserted after the last TS packet in the multiplex block.

The present embodiment has been described primarily with reference torecording to DVD, but the invention will obviously not be so limited.More specifically, after recording a self-encoded transport stream to ahard disk, semiconductor memory, or other data recording medium, astream converted to an MPEG program stream can be recorded to the samemedium or to a different medium.

Furthermore, the PAT, PMT, and UP packets are described as recorded tothe beginning of each VOBU in the present embodiment, but they can berecorded to the beginning of at least a VOB or to the beginning of aCell which is the playback management unit.

Yet further, this embodiment is described recording PAT, PMT, and UPpackets, but the UP packet can be omitted.

Yet further, the PAT, PMT, and UP packets are described as fixed at thebeginning in the present embodiment, but the invention shall not be solimited, and a packet storing a Null packet can be recorded insertedtherebetween.

Yet further, a self-encoded stream is described starting from a PATpacket, but the invention shall not be so limited and the stream couldstart from a Null packet.

Furthermore, the system transfer rate can be set to a fixed rate byappropriately inserting Null packets in the self-encoded stream.

It should also be noted that a data area for storingmanufacturer-private information can be provided as shown in FIG. 7, andMPEG_TS system encoding conditions can be written to this data area.

It should also be noted that all or part of the information written tothe UP packet in the above embodiment can be written to the TS1_VOBinformation shown in FIG. 15.

It will also be noted that the DVD Video format does not allow for dualmono audio. It is, however, possible to convert a self-encodingtransport stream recorded with dual mono audio channels to the DVD Videoformat by separating the dual mono audio channels into two separateaudio streams recorded as left and right monaural audio channels.

Part or all of the parameters written to the UP packet in the aboveembodiment could also be written into the management information. Bythus avoiding recording a parameter that does not change within aself-encoding transport stream multiple times, recording space is notwasted and the decoder does not need to waste processing time trying todetermine whether or not the parameter changed each time a UP packet isdetected.

Second Embodiment Encoder Configuration

An alternative embodiment of the present invention is described nextbelow. The description is made to an encoder of a data recordingapparatus according to the present invention by focusing first theencoding process to receive and self-encode AV input to an MPEGtransport stream.

FIG. 33 shows the configuration of the encoder in a data recordingapparatus according to the present invention. As shown in the figure theencoder 214 includes elementary stream encoders 230 a, 230 b and 230 c,and a system encoder 232. The encoder 214 receives a control signal fromthe system controller 212 and then runs the encoding process with theelementary stream encoders 230 a, 230 b and 230 c, or the system encoder232 while switching between elementary encoding and system encoding.Each of the elementary stream encoders 230 a, 230 b and 230 c receivesvideo, audio, and VBI (Vertical Blanking Interval) signals for encoding.

The video encoder 230 a receives a control signal from the systemcontroller 212 and based thereon encodes the bit rate, resolution,aspect ratio, and other attributes of the video stream within apredefined range. More specifically, the video encoder 230 a receives acontrol signal from the system controller 212 specifying the operatingmode as the “DVD Video compatible mode,” DVD Video Recording compatiblemode,” or “normal mode.” If the mode specified by the control signal isthe DVD Video compatible mode, the video encoder 230 a generates a videostream conforming to the video attributes of the DVD Video standard; ifthe DVD Video Recording compatibility mode, it generates a video streamconforming to the video attributes of the DVD Video Recording (“DVD VR”below) standard; and if the normal mode, generates a video streamconforming to a specific attribute range.

The audio encoder 230 b likewise receives a control signal from thesystem controller 212 and based thereon encodes the bit rate,quantization rate, channel count, and other attributes of the audiostream within a predefined range. Like the video encoder 230 a, theaudio encoder 230 b specifically receives a control signal from thesystem controller 212 specifying the operating mode. If the modespecified by the control signal is the DVD Video compatibility mode, theaudio encoder 230 b generates an audio stream conforming to the audioattributes of the DVD Video standard; if the DVD VR compatibility mode,it generates an audio stream conforming to the audio attributes of theDVD Video Recording (“DVD VR” below) standard; and if the normal mode,generates an audio stream conforming to a specific attribute range.

The VBI data encoder 230 c likewise receives a control signal specifyingthe operating mode from the system controller 212 and encodes the VBIdata accordingly. Specifically, if the elementary stream encodingcontrol signal input from the system controller 212 to the VBI dataencoder 230 c indicates the DVD Video compatible mode or DVD VRcompatible mode, it additionally encodes VBI data according to the VBIdata storage method specified by the respective standards. There is acase that a VBI data storage method is separately defined even in theoriginal normal mode, and in that case “additionally encode” means thatVBI data is redundantly stored to the elementary stream.

The encoded elementary streams are then multiplexed to the MPEG_TSsystem stream by the system encoder 232.

Like the elementary stream encoders 230 a, 230 b and 230 c, the systemencoder 232 also receives an encoding control signal from the systemcontroller 212 to encode according to the received signal.

The control signal from the system controller 212 to the system streamencoder 232 is either a system encoding control signal for encoding anormal MPEG_TS, or a system encoding control signal (DVD-Video mode orDVD-Video Recording mode) applying constraints on the normal MPEG_TS inorder to enable easy conversion to an MPEG_PS (particularly a specificDVD format).

If the control signal is for encoding a normal MPEG_TS, the systemstream encoder 232 applies the system encoding to the elementary streamsinput from the elementary stream encoders 230 a, 230 b and 230 c whilemanaging the buffers so that the input streams are not corrupted by thedecoder model (T_STD) which is a reference for the MPEG_TS systemstream.

If the control signal from the system controller 212 is a control signalspecifying system encoding to an MPEG_TS enabling easy conversion to anMPEG_PS, the encoding is conducted while also following additionalspecial system encoding rules.

The encoder 214 then outputs the resulting self-encoding MPEG_TS systemstream.

The data recording apparatus according to the present invention is thuscharacterized by switching the encoding mode at the elementary streamand system stream encoding levels. The processes applied in eachencoding mode to convert to a particular DVD format when the encodingmode is changed as described above are shown in the table in FIG. 34.

An MPEG_TS enabling easy conversion to an MPEG_PS is thus generated bydriving the elementary stream encoders 230 a, 230 b and 230 c and systemencoder 232 to encode the respective streams assuming the conversion toan MPEG_PS.

<A Self-Encoded MPEG_TS>

A detailed embodiment of the format of an MPEG_TS self-encoded by a datarecording apparatus according to the present invention is described nextbelow. The differences between a normal MPEG_TS (“SESF” below) and anMPEG_TS enabling easy conversion to an MPEG_PS (a “Constrained SESF”below) are also described.

In the following example, information presenting the stream encodingconditions is stored to the VOBI storing attributes and otherinformation in MPEG_TS stream units. By thus storing information aboutthe encoding conditions to the management information and not in thestream, it is possible to quickly determine whether a stream can beeasily converted to a DVD Video or DVD VR format without analyzing thestream. Note that this information presenting the stream encodingconditions can be stored to a Tip packet which is described furtherbelow.

The information presenting the stream encoding conditions is representedby an “encode_condition” flag which has two bits. The flag value isdescribed below.

00b: normal MPEG_TS (SESF)

01b: MPEG_TS enabling easy conversion to a DVD VR stream format(Constrained SESF)

10b: reserved

11b: MPEG_TS enabling easy conversion to a DVD Video stream format(Constrained SESF)

Two cases are possible if the encode_condition flag is set to 00b in thestream management information: the stream is originally encoded withoutconsidering high speed conversion to MPEG_PS, and a sequence of MPEGprogram streams are linked by user editing for easy conversion toindividual MPEG program streams.

If the encode_condition flag is also set in the stream, it ismeaningless to set encode_condition=00b indicating a normal MPEG_TS inthe stream. It is therefore also possible for the encode_condition flagto be used differently inside and outside the stream, reserving theencode_condition=00b setting so that it is not used in the stream (inthe Tip packet described below).

By thus setting this flag, it is possible to determine from the value ofthe VOBI encode_condition field whether the stream can be easilyconverted to a DVD Video or DVD VR format. “Easily converted” as usedherein means convertible by the conversion method described furtherbelow.

<Constrained SESF Stream Structure>

FIG. 80 shows the complete stream structure of a Constrained SESF. AConstrained SESF includes plural SESF capsules. An SESF capsule containsspecific multiplexing units, and a Tip packet (detailed below) at thehead. The presentation time stamp (PTS) of each SESF capsule and anaddress of the Tip packet are correlated in the access map 80 c. Asdescribed below, for TS2PS conversion, a conversion process isaccomplished in SESF capsule units.

FIG. 32 shows the correlation between MPEG_PS packs and packets in onSESF capsule. As shown in FIG. 32 a TS packet (Tip packet below) storingstream-specific information is inserted to a Constrained SESF. The Tippacket embedded in a Constrained SESF is described below with referenceto FIG. 35 to FIG. 41.

<Tip Packet>

FIG. 35 shows the overall Tip packet structure. As shown in FIG. 35, aTip packet stores a Data_ID identifying the packet as a Tip packet,display_and_copy_info corresponding to the DVD VR DCI_CCI field andincluding display control and copy control information, encode_infostoring stream encoding information, and MakersPrivateData for storingadditional information unique to the manufacturer.

As shown in FIG. 35 and FIG. 36, the PCR value needed for the SCRcalculations described below is written to the adaptation field of theTip packet. This adaptation field is a fixed byte length, and therebyenables accessing information in the Tip packet using a fixed address.

The Data_ID structure is shown in FIG. 37. The Data_ID has aData_Identifier for identifying whether the corresponding packet is aTip packet. The Data_Identifier is a 3-byte field holding a value of“0x544950” expressing “TIP” in the ASCII code. The decoder of theplayback device reads the value of this field to identify that it is aTip packet.

The display_and_copy_info structure is shown in FIG. 38. Generating theRDI pack when converting a Constrained SESF to the DVD VR format issimplified by providing the same structure and information as theDCI_CCI field of the RDI Unit in the DVD VR standard indisplay_and_copy_info. (Note that the DCI_CCI field of the DVD VRstandard is fully described in “DVD Specifications forRewritable/Re-recordable Disc, Part 3, VIDEO RECORDING,” and in Japanesepatent No. 3162044. While some of the field names are different in thesedocuments, the field definitions are the same so as to enable directcopying when converting to the DVD VR format.)

The encode_info field structure is shown in FIG. 39. Resolutioninformation for the video stream following the Tip packet is written tothe video_resolution field. The value of encode_info is shown below.

0000b: 720×480 (NTSC), 720×576 (PAL)

0001b: 704×480 (NTSC), 704×576 (PAL)

0010b: 352×480 (NTSC), 352×576 (PAL)

0011b: 352×240 (NTSC), 352×288 (PAL)

0100b: 544×480 (NTSC), 544×576 (PAL)

0101b: 480×480 (NTSC), 480×576 (PAL)

Others: reserved

Resolution can vary during a single continuous recording in the DVD VRformat. However, streams of different resolutions are managed asseparate VOBs and it assures seamless connection during playback by acertain recorder. This field is therefore used to determine where it isnecessary to split the VOB when converting to the DVD VR format, ifthere is a resolution change during Constrained SESF recording.

In a Constrained SESF recorded with consideration for converting to theDVD Video format (encode_condition=11b), the resolution does not changewithin a single stream.

The encode_condition field is the same as the value stored to the VOBI(except when 00b). The reason why the encode_condition field is storedand embedded in the stream and not only in the stream managementinformation is to enable the recorder to easily determine if it ispossible to convert to the DVD format by referencing theencode_condition field in the Tip packet when, for example, a stream iscopied through a digital interface such as IEEE 1394.

VOBU_S_PTM of the DVD VR standard is recorded to the FVFPST field. Thisis to eliminate the process of analyzing the video stream encoded afterthe Tip packet and calculating the presentation time of the firstappearing video field when converting a Constrained SESF to a DVD Videoor VR format.

The FVFPST field includes a 32-bit field denoting the video fieldpresentation time at 90 KHz precision, and a 16-bit field denoted at 27MHz precision.

The PES_info structure is shown in FIG. 40. PES_info is needed toconvert a Constrained SESF to the DVD Video format without analyzing theelementary streams. This information is needed to generate theinformation inserted to the DVD Video stream and stored in the packs,referred to as NV_PCK, supporting special playback modes.

The PES_info can store information for 136 PES packets each storingvideo data or audio data units. Four bits are assigned to each PESpacket, and the NV_PCK information can be generated without analyzingPES packet content. PES packets not storing video or audio data areignored.

In a SESF capsule being the data unit from one Tip packet to the packetimmediately preceding the next Tip packet, a PES_existence_flag declaresif the j-th PES packet is present in the SESF capsule. The value ofPES_existence_flag is set as follows.

0b: j-th PES packet is not in the SESF capsule

1b: j-th PES packet is in the SESF capsule

If the PES_extension_flag=0b (when there is no PES packet), allremaining fields in the PES packet are set to 0b.

The PES_payload_identifier identifies whether the data stored in the PESpacket is video or audio data. PES_payload identifier values are set asfollows.

0b: video stream

1b: audio stream

The PES_existence_flag and PES_payload_identifier fields are set for allrelevant PES packets.

When it is determined from the PES_payload_identifier whether video oraudio data is stored, the remaining field definitions vary according tothe type of stream stored in the PES packet.

If the PES packet stores a video stream (PES_payload_identifier=0b),picture_coding_type indicating the type of picture stored in the PESpacket is defined after the PES_payload_identifier field.

The value of the picture_coding_type field is set as follows.

00b: a picture encoded with encoding other than 01b or 10b

01b: a frame encoded I-picture; a pair of field encoded I-pictures; or apair of field encoded I-picture and field encoded P-picture

10b: a pair of frame encoded P-pictures or a pair of field encodedP-pictures

11b: reserved

In other words, a picture with 01b or 10b is a picture used as thereference picture defined by the DVD Video standard. The abovedescription is for information added to PES packets storing video.

If the PES packet stores an audio stream (PES_payload_identifier=1b),the PES_payload_identifier is followed by a stream identifier and async_presentation_flag. The stream_identifier identifies whether theaudio stream in the PES packet is a first audio stream or a second audiostream. The sync_presentation_flag is a flag to identify whether thereis an audio frame for which presentation begins simultaneously to orimmediately following the FVFPST field (the presentation start time ofthe video field presented first) written to each Tip packet.

The value of stream identifier is set as follows.

0b: first audio stream

1b: second audio stream

The first and second audio stream can be discriminated by the PIDsetting rules and the order of elementary stream declaration in the PMT.

The value of sync_presentation_flag is set as follows.

0b: an audio frame for which presentation begins simultaneously to orimmediately following the FVFPST is not stored in the audio PES packet

1b: an audio frame for which presentation begins simultaneously to orimmediately following the FVFPST is stored in the audio PES packet

Information added to PES packets storing audio is as described above.

The PES_info field thus extracts and stores information for each PESpacket following a Tip packet.

FIG. 41 shows the MakersPrivateData. As shown in the figure, theMakersPrivateData has a maker_ID field identifying the manufacturer ofthe Constrained SESF, and maker_private_data field containing specificadditional information described by the manufacturer.

FIGS. 42A and 42B shows an example of a value of PID of the Tip packetand a value of stream_type indicating the stream type. Other PID andstream_type values are reserved by the MPEG standard and otherstandards, and these values were selected to indicate private databeyond the scope of the MPEG standard without interfering with reservedvalues.

Various stream attribute information is thus extracted and stored to theTip packets stored in a Constrained SESF. How the fields described aboveare used during conversion to a different DVD format is described infurther detail below.

<System Encoding Conditions>

The system encoding conditions for a Constrained SESF are described indetail next below. Note that the following system encoding conditions donot apply to a normal SESF.

<Multiplexing Unit>

TS packet storing elementary streams in a Constrained SESF is composedof a Multiplexing Unit which is a unit of data stored in 2 KB packsaccording to a DVD format. Note that this Multiplexing Unit correspondsto the multiplex block of the first embodiment.

Only TS packets storing one type of elementary stream are stored to eachMultiplexing Unit, and these TS packets are not mixed with TS packetsstoring another type of elementary stream. Mixing TS packets with Nullpackets is not prohibited because it may be necessary to include one ormore Null packets in order to generate a Multiplexing Unit (such as theMultiplexing Unit storing the last part of a stream). This is necessaryto clarify the relationship between Multiplexing Units and packs.

One Multiplexing Unit contains eleven continuous TS packets, and theelementary stream (payload data) in each Multiplexing Unit is storedcompletely within the one corresponding pack. This likewise constrainsthe relationship to the pack.

When the PES packet storing the video stream is segmented and placed inmultiple Multiplexing Units, all Multiplexing Units other than theMultiplexing Unit containing the last byte of the PES packet store a TSpacket payload data of 184×11=2024 bytes. This allows stream transfersto be completed most efficiently and successive processing by TS packetunit to be easily accomplished during TS2PS conversion. If the size ofMultiplexing Units other than the last Multiplexing Unit is less than2024 bytes, it will not be possible to easily determine the value of thePES_packet_length field stored to the packet header of each pack in theMPEG_PS when converting the first TS packet of the Multiplexing Unitduring TS2PS conversion.

The first complete audio frame data in the Multiplexing Unit should bean audio frame placed at the beginning in the payload of PES packet.This is easy to understand by considering storing PES packets storingthe audio stream to multiple Multiplexing Units. If one audio PES packetis segmented and placed in multiple Multiplexing Units, it is necessaryto identify the PTS and determine the number of audio frames stored inone pack in order to generate the packet header when converting thesecond and later Multiplexing Units to MPEG_PS packs. Hence, it shouldbe avoided that it is necessary to analyze the internal structure of theaudio stream and then conversion process is complicated.

The Multiplexing Unit is defined above. Encoding to generate aConstrained SESF involves system encoding within the constraints of theabove-described Multiplexing Unit.

<Constraints of PES Packet Headers in a Constrained SESF>

A number of constraints on the field values of the PES packet header ina Constrained SESF are described next.

As shown in FIG. 43, some PES packet header fields allow only fixedvalues. This is to prevent creating unnecessary processes whenconverting to different DVD formats. “Unnecessary processes” meansprocessing fields additionally created or deleted by values differentfrom values defined by the DVD format. In other words, the purpose ofthis PES packet header constraint is to minimize fields added to ordeleted from the header during TS2PS conversion.

A value of 0 is permitted for the PES_packet_length field when a videostream is stored to the MPEG_TS.

The PTS_DTS_flags field indicates if a PTS or DTS is included.

When the PES packet stores an audio frame, at least one or more audioframes starts in the PES packet, and PTS_DTS_flags is set to 10b (to 11bif the DTS is written).

Constraints for sequentially processing by TS packet unit during TS2PSconversion are applied to PES_extension_flag and PES_header_data_length.These are shown in FIG. 44.

As shown in FIG. 44, specific values are defined according to theelementary stream type, PES packet location, and encode_condition value.

Note that VPD in FIG. 44 is the combined byte length of the PTS fieldand DTS field in the PES packet. That is,

if PTS_DTS_flags=00b, VPD=0;

if PTS_DTS_flags=10b, VPD=5;

if PTS_DTS_flags=11b, VPD=10.

As described above, this constraint is necessary to simplify sequentialprocessing by TS packet unit without forming the packs after determiningthe payload length of one pack when converting to the DVD Video or VRformat.

The PES packet header is defined above. An encoder generating theConstrained SESF encodes the system stream within the above constraints.

<Constraints on the Tip Packet Insertion Interval>

Constraints on the insertion interval of Tip packets inserted to aConstrained SESF are described next.

The following relationship must be true for the decoder input timeindicated by ATS (ATS1) of the Tip packet, and the decoder input timeindicated by ATS (ATS2) of the TS packet storing the video or audiostream input to the decoder first after the Tip packet.

ATS1+T≦ATS2

T=(PS_pack_size*8*system_clock_frequency)/PSrate

where T is the shortest PS pack transfer period. This shortest transferperiod is the shortest period from the start to the end of PS pack inputto the system decoder. That is, the above equation shows that the ATSinterval of each TS packet must at least be greater than the interval atwhich PS packs after conversion can be input to the system decoder.

The value of T is determined as follows.

PS_pack_size is the byte length of one pack in the MPEG_PS generated byTS2PS conversion, the system_clock_frequency is the frequency of thereference clock of the MPEG_PS decoder, and PSrate is the multiplex rateof the MPEG_PS stream generated by TS2PS conversion.

These values are defined as below by the DVD format, and therelationship between ATS1 and ATS2 is therefore as follows.

PS_pack_size=2048 bytes

system_clock_frequency=27,000,000 Hz

PSrate=10,080,000 bits/second

ATS1+43885.714 . . . <ATS2

Therefore,

ATS1+43886 . . . ≦ATS2

defines the minimum value of ATS2. The TS2PS conversion described belowtypically converts a Tip packet to a 2-KB NV_PCK (in DVD Videoconversion) or RDI_PCK (in DVD VR conversion) pack. However, if theabove relationship is not satisfied, the next elementary stream istransferred earlier and may exceed the upper limit of the DVD systemtransfer rate (10.08 Mbps).

An integer number of GOPs are aligned in one SESF capsule. This is tomake the SESF capsule correlate to a VOBU of the DVD format so that theVOBU concept of the DVD format can also be realized in the ConstrainedSESF. More particularly, a VOBU must include an integer number of GOPsaccording to the DVD format (DVD VR).

Video data stored in one SESF capsule must be at least 0.4 second andnot more than 1.0 second wide on the playback time base. In addition,the time width on the playback time base of video data stored in thelast SESF capsule is greater than or equal to 0.4 second and less thanor equal to 1.2 second when the encode_condition=11b (DVD Video mode),and when the encode_condition=01b (DVD VR mode) must be less than orequal to 1.0 second. This is because the SESF capsule becomes a VOBU,and must conform to the specific DVD format.

Each Tip packet normally preferably has a 1:1 correlation on the accessmap used for time-address conversion. This is required so thatconversion can start immediately with the VOBU units defined by the DVDformat during TS2PS conversion, and so that the DSI (Data SearchInformation) (which provides address information for the adjacent VOBUstored in the NV_PCK) can be generated from the access map when Tippackets are converted to NV_PCK packs during conversion to the DVD Videoformat. The DSI can be calculated insofar as the access map stores theplayback time (part or all of the AV playback time informationimmediately after the Tip packet according to FVFPST) for each Tippacket and recording address of each Tip packet, and the number ofMultiplexing Units stored between two consecutive Tip packets is known.This is achieved by imposing the following constraints.

It should be noted that all Tip packets need not be pointed to from theaccess map. For example, AV data following the last Tip packet in aConstrained SESF does not contain playback time length information norhave a next Tip packet, is thus different from other Tip packets and istherefore handled differently. In this case, no particular adverseaffect on playback and conversion even if the last Tip packet is notregistered in the access map, and thus it can be handled in anexceptions process in consideration with the device implementation.

A total thirty-two packets not associated with a Multiplexing Unit areinserted between two consecutive Tip packets. This is because it isnecessary to determine how many packs there will be in a VOBU whenconverted to a DVD format using the access map during TS2PS conversion.(The number of packets need not be limited to 32, but there must be somespecific number of packets. Because the number of TS packets following aTip packet can be determined from address information of the Tip packetin the access map, the number of packs included in a VOBU when convertedto a DVD format can be determined if the number of packets that are notMultiplexing Units is known. This is important. This information may bedescribed in MNF or MakersPrivateData in each Tip packet.)

Furthermore, the reason there are 32 packets is as follows. It could besufficient that there are at least 31 PAT, PMT, PCR, and SIT packetsbetween two consecutive Tip packets, because: the PAT, PMT packetsdescribing the MPEG_TS program configuration data must be embedded atleast once every 100 msec; a SIT packet storing specific information foreach program must be embedded at least once every 1 second; the PCRpacket storing the PCR (program clock reference) establishing thedecoder reference time must be embedded at least once every 100 msec;Null packets not belonging to any Multiplexing Unit can be freely added;and the Tip packet insertion interval is 1.0 second or less on the AVdata playback time base. Therefore, count of the VOBU pack can bedetermined from the access map by inserting PAT, PMT, PCR, and SITpackets between two consecutive Tip packets according to these definedtimes, and adding Null packets until there are 32 packets.

Consider, for example, the number of packs after conversion when a Tippacket is inserted at 0.5 second intervals and there are 1209 TS packetsfollowing a Tip packet identifiable from the access map. In this casethere is a total of 15 (=5+5+5) PAT, PMT, and PCR packets, 1 SIT packetinserted after this Tip packet, and 16 Null packets inserted to achievea total 32 packets. When this is then converted to DVD format, the Tippacket is converted to an NV_PCK (when converted to DVD-Video) orRDI_PCK (when converted to DVD VR) as one pack, and one MultiplexingUnit (11 TS packets) is converted to one pack, respectively. The countof VOBU pack can therefore be denoted as

1+(number of Multiplexing Units).

The number of Multiplexing Units is

(number of TS packets following that Tip packet−33)/11.

In this example, therefore, there are

1+((1210−33)/11)=1+107=108.

It thus can be determined that the VOBU has a total 108 packs. If thenumber of packs in each VOBU and the presentation start time informationis known, the DSI packet of the NV_PCK required for conversion to DVDVideo can be generated very quickly.

The constraints on the Tip packet insertion interval are as describedabove. The encoder generating the Constrained SESF encodes the systemstream within the above constraints.

<Constraints on Decoder Control>

Constraints on decoder control (buffer management) of Constrained SESFare described next below.

A Constrained SESF must be generated to satisfy the standard of T_STDthat is the decoder reference model for an MPEG_TS. This means that theConstrained SESF can be decoded by a set-top box, for example, having aT_STD conforming decoder if the stream types match.

The MPEG_TS standard decoder model T_STD and the MPEG_PS standarddecoder model P_STD are substantially the same in operation andprocessing capabilities, but the audio stream input rate to the decoderdiffers. More specifically, the transfer rate of the T_STD from thetransport buffer before the audio decoder to the audio buffer is 2 Mbps(except for AAC) (see FIG. 18). The P_STD, however, inputs each streamto the decoder at the system rate, which with DVD is 10.08 Mbps.

This means buffer management of a Constrained SESF and DVD format cannotbe the same.

The same buffer management thus cannot be used with an MPEG_TS andMPEG_PS. However if the SCR (System Clock Reference) indicating thedecoder input time of the pack after conversion can be calculated usingthe ATS added to each TS packet while avoiding system encoding withre-consideration of buffer management during the conversion from aConstrained SESF to DVD format, very quick and easy conversion can beachieved. Calculating the SCR using the ATS is described in detailfurther below.

Furthermore, the Constrained SESF of the present invention must beencoded so as to assure that it conforms to the T_STD and also that theMPEG_PS generated by the conversion method described further belowconforms to P_STD.

More specifically, the Constrained SESF is a stream encoded to a MPEG_TSso that it also conforms to the P_STD after conversion to an MPEG_PS.

These are the constraints on Constrained SESF buffer management. Itshould be noted that a normal SESF is simply encoded to conform to theT_STD without considering these constraints.

Examples of MPEG_TS and MPEG_PS that do not conform to the standardT_STD and P_STD models are described below.

First, an example of a MPEG_TS self-encoded such that it can beconverted to an MPEG_PS but does not conform to the T_STD model is shownin FIG. 45. Stream TS1 is an MPEG transport stream applied withsystem-encoding to conform with the T_STD model. Stream TS2 is an MPEGtransport stream that does not conform to the T_STD model. Morespecifically, in the stream TS2, the values of ATS [47] to ATS [57] areset above the transfer rate allowed for MPEG_TS audio data. The audiotransport buffer thus overflows (FIG. 18) and the stream does notconform to the T_STD model. In stream TS1, however, the values of ATS[47] to ATS [57] are set within the transfer rate allowed for MPEG_TSaudio data. This stream can therefore be correctly converted to a P_STDconforming MPEG program stream PS1 using the SCR conversion equationdescribed below. Furthermore, while stream TS2 does not meet the T_STDstandard, PS1 can be generated by conversion using the below SCRconversion equation. For conversion from stream TS2 to MPEG_TSconforming with a T_STD, the audio packet transfer time intervalspecified by ATS [47] to ATS [57] must be increased so that a transportbuffer overflow does not occur.

FIGS. 46A and 46B shows an example in which the T_STD model is satisfiedbut the MPEG_PS converted from an MPEG_TS does not satisfy the P_STDmodel. Stream TS3 is an MPEG transport stream, and stream PS3 is an MPEGprogram stream converted from MPEG transport stream TS3. FIG. 46B showsthe change in the state of a buffer for video data for each streamduring decoding. The PES #1 picture is decoded at time SCR [2], and thePES #2 picture is decoded between SCR [4] and SCR [5]. As shown in FIG.46B, transfer of TS packet data in transport stream TS3 is completed bythe time picture data in PES #1 and PES #2 is decoded. With programstream PS3, however, V_PCK #1 data transfer for PES #1 is in time, buttransfer of V_PCK #4 for PES #2 data is late for decoding and a bufferunderflow occurs because decoding starts while the data transfer is inprogress. The requirements of the P_STD model are therefore not met.This can be avoided by shifting the value of the ATS field (ATS [14],ATS [25], ATS [36]) for each TS packet converted to V_PCK #2 to V_PCK #4so as to be temporally earlier, so that transferring the MPEG_TS PES #2picture data is completed earlier.

<ATS-SCR Conversion>

Calculation method of the SCR of PS packet when converting a ConstrainedSESF stream to a program stream is described below. The SCR must becalculated in order to generate a new pack, and is therefore necessaryonly when converting Tip packets and the first TS packet in aMultiplexing Unit.

The structure of a Constrained SESF stream is as shown in FIG. 14C. APCR packet storing reference time information (program clock referencePCR) is appropriately inserted to a TS packet, and this can be used toreset the decoder reference time STC (system time clock) at anappropriate time interval. Each TS packet also contains an ATS storingthe relative transfer time information between each TS packet.Therefore, TS packets output after the TS packet storing the PCR areinput to the decoder at a timing determined from the PCR and ATSindicating the relative transfer time between TS packets. In otherwords, the decoder input time (the “calculated_PCR” below) of each TSpacket can be generated for TS packets from the TS packet storing thePCR. If no TS packet stores the PCR, information equivalent to the PCRcan be extracted to the management information.

FIG. 47 shows the relationship between the calculated_PCR and SCR whenconverting a Constrained SESF to MPEG_PS, i.e., a head of the SESFcapsule shown in FIG. 80. The ATS assigned to each TS packet inascending order from the stream start is denoted ATS [k]. The PCRcalculated in order of appearance for the first TS packet in aMultiplexing Unit is denoted calculated_PCR [i] (i=0, 1, 2 . . . ). TheSCR of the pack after conversion is likewise denoted SCR [i].

As noted above, video stream transfers are constrained by the maximumtransfer rate of 15 Mbps (in the case of MP@ML, the transfer rate fromthe multiplexer buffer to the video buffer does not exceed 15 Mbps) andthe audio stream input rate is lower than the video transfer rate.(Except for AAC, the transfer rate from the transport buffer to theaudio buffer does not exceed 2 Mbps.) Multiplexing units storing audiodata are therefore different from Multiplexing Units storing video dataand are transferred at a lower rate. Therefore, if the video datatransfer rate is raised to near the 9.8 Mbps maximum rate of the DVDformat, TS packets of video data must be transferred at a rate above theDVD transfer rate (10.08 Mbps) in order to assure sufficient time foraudio data transfers which occur at a lower rate and therefore take moretime.

That the transfer time differs in Constrained SESF and the DVD formatwill be known from FIG. 47.

The following relationship must be true for the decoder arrival time(calculated_PCR) of the first TS packet in a Multiplexing Unit or Tippacket, and the SCR of the pack after that packet is converted.

SCR[0]=calculated_PCR[0]

SCR[i]=max(SCR[i−1]+T, calculated_(—) PCR[i]) (i=1, 2, 3, . . . )

calculated_(—) PCR[i]=PCR_tip+(ATS[i]−ATS_tip+WA*BS)

T=PS_pack_size*8*system_clock_frequency/PSrate

where PCR_tip and ATS_tip are the PCR value and the ATS of the Tippacket immediately before the converted Multiplexing Unit. WA indicateshow many times overflow occurred (described further below) in a rangebetween ATS_tip and the ATS (ATS [i]) assigned to the first TS packet inthe i-th Multiplexing Unit. BS denotes the amount of one overflow inATS. max(a,b) is a function for selecting the greater of a or b.

In the SCR [i] (i=0, 1, 2, 3, . . . ) relation, PS_pack_size is the bytelength of one pack in the MPEG_PS generated by the TS2PS conversion asnoted above, system_clock_frequency is the frequency of the MPEG_PSdecoder reference clock, and PSrate is the multiplex rate of the MPEG_PSgenerated by TS2PS conversion. That is,

PS_pack_size=2048 bytes

system_clock_frequency=27,000,000 Hz

PSrate=10,080,000 bits/second

There are, therefore, two patterns for transferring packs after thefirst pack: transferring the pack after a minimum transfer timedetermined by the transfer rate passes from the transfer time of the onepreceding pack, or transferring the pack at the decoder input time ofthe first TS packet in the pack. For pack transfers at a time before thetime when the video data is converted to the DVD format, packs aretransferred at the minimum transfer time interval noted above. Forexample, when packs are transferred in a time band preceding video dataconversion to the DVD format, packs are transferred after waiting theminimum transfer time determined by the transfer rate from the time whenthe preceding pack was transferred.

It should be noted that because a Constrained SESF can be edited, thecalculated_PCR [0] may not go to 0 even when recorded withencode_condition=11b, if the beginning of the stream is deleted byediting, for example.

However, if calculated_PCR[0] is not zero while encode_condition=11b,this problem can be resolved by applying the following conversionequation only when encode_condition=11b.

SCR[0]=0

SCR[i]=max(SCR[i−1]+T, calculated_(—) PCR[i])−calculated_(—) PCR[0]i=1,2, 3, . . . )

calculated_(—) PCR[i]=PCR_tip+(ATS[n]−ATS_tip+WA*BS)

T=PS_pack_size*8*system_clock_frequency/PSrate

PTS(DVD-Video)=PTS(Constrained SESF)−calculated_(—) PCR[0]

DTS(DVD-Video)=DTS(Constrained SESF)−calculated_(—) PCR[0]

As described above, ATS[n] and WA are ATS value of first TS packet ini-th Multiplexing Unit and number of overflows based on ATS_tip,respectively.

In other words, to conform to the DVD Video format, SCR[0] set to 0,values of subsequent SCRs are offset values, and all PTS and DTS in theDVD Video stream are offset by a uniform time of calculated_PCR[0] usingthe result of the above conversion equation offset timecalculated_PCR[0].

By thus uniformly offsetting the time information of the stream,conversion to the DVD Video format while keeping encode_condition=11b ispossible even when the beginning of the Constrained SESF(encode_condition=11b) has been deleted.

PTS and DTS values may be converted during conversion to the DVD Videoformat, but this can be easily achieved by sequentially processing theTS packet units.

The SCR is calculated from the ATS based on the above equation duringTS2PS conversion. The program stream output by TS2PS conversion mustconform to the P_STD model as noted above, and this means that SCRvalues are restricted to a particular range. The ATS values assigned toeach packet of a Constrained SESF must therefore be set according to theATS-SCR relation shown above.

<Elementary Stream Constraints>

Constraints on the elementary streams of a Constrained SESF aredescribed next.

Because re-encoding the elementary streams imposes an extremely heavyburden on the encoder, only MPEG-2 Video is allowed for video data whileAC-3, MPEG-1 Audio, and LPCM are allowed for audio data.

The Constrained SESF described here excludes LPCM, however. This is toavoid the danger of needing to re-encode the elementary stream when LPCMuses a quantization rate of 20 bits or more, and to simplify buffermanagement by reducing the amount of audio data for which the transferrate cannot be raised. If 16-bit LPCM is used, however, there is noparticular need to exclude LPCM audio.

Streams permitted for the Constrained SESF described here are MPEG-2Video for the video data, and two types of audio data, AC-3 and MPEG-1Audio.

In normal SESF which is not Constrained SESF, encoding of audio data isnot limited to the above. Encoding method such as AAC (Advanced AudioCoding) which is used in BS digital broadcasting can be used.

Elementary stream attributes when encode_condition=11b are shown in FIG.48.

Because the attributes shown in the figure are set to assureinterchangeability at the elementary stream level between DVD Video andDVD VR, a Constrained SESF (encode_condition=11b) conforming to theseattributes does not require elementary stream re-encoding when convertedto DVD Video or DVD VR formats, and high speed conversion is thereforepossible.

Elementary stream attributes when encode_condition=01b are shown in FIG.49.

Because the attributes shown in the figure are set to assureinterchangeability at the elementary stream level with DVD VR, aConstrained SESF (encode_condition=01b) conforming to these attributesdoes not require elementary stream re-encoding when converted to DVD VRformat, and high speed conversion is therefore possible.

Notes 1 to 4 in FIG. 48 and FIG. 49 are described below.

Note 1: This attribute cannot change within the same VOB.

Note 2: This attribute can change in the TS packet storing the firstelementary stream following the Tip packet. In other words, it canchange only in the first video or audio TS packet in an SESF capsule.

Note 3: sequence_end_code cannot be inserted between sequence_headerfields having the same horizontal_size, vertical_size, andaspect_ratio_information.

Note 4: This attribute can change within the same VOB for monaural,stereo, and dual monaural.

Constraints relating to the elementary streams of a Constrained SESF aredescribed above.

Adding the encoding conditions described above makes it possible togenerate a Constrained SESF that can be easily and quickly converted toa DVD format.

<DVD Video and DVD VR Format After Conversion>

The field settings of the DVD Video and DVD VR formats to which theConstrained SESF is to be converted are described next.

<DVD Video Format>

A stream conforming to the DVD Video standard is described briefly firstbelow. The DVD Video stream format is described in detail in “DVDSpecifications for Read-Only Disc, Part 3, VIDEO SPECIFICATIONS.”

The stream structure of the DVD Video format is shown in FIG. 50. Asshown in the figure each stream contains multiple VOBs and each VOBcontains an integer number of VOBU. A VOBU includes an integer number ofpacks, starting with a NV pack (V_PCK) followed by a video pack (V_PCK)an audio pack (A_PCK). Unlike a normal DVD pack, the NV_PCK contains twopackets. These packets are called the PCI (Presentation ControlInformation) and DSI (Data Search Information) packets, respectively.The playback control information for the corresponding VOBU is stored tothe PCI packet. Information useful for special playback modes, such asthe relative positions of the VOBU to neighboring VOBU, is stored to theDSI packet. These fields are described next below in conjunction withhow the field values are determined.

FIG. 51 shows the structure of NV_PCK PCI data. The PCI data includesPCI_GI (PCI General Information) storing general information for PCI,NSML_AGLI as angle information for non-seamless presentation, HLI asinformation for adding highlighting to menus and buttons, and RECIstoring the International Standard Recording Code (ISRC).

When converted from Constrained SESF, NSML_AGLI and HLI store a valueindicating an invalid.

The ISRC field can store a value indicating an invalid or a ISRC code asit is, but this field is irrelevant to conversion from Constrained SESFand further description is therefore omitted. The only field that aproblematic with respect to creating PCI data from a Constrained SESF istherefore the PCI_GI field.

FIG. 52 shows the structure of the PCI_GI field in NV_PCK. Note thatcalculation methods are described below only for those fields that mustbe calculated during conversion from a Constrained SESF.

11/17

NV_PCK_LBN (the relative address of NV_PCK in the VOBS file) can bedetermined by the data recording apparatus which counts each pack numberduring conversion.

VOBU_CAT (information of the analog copy protection state) can beobtained from the display_and_copy_info of the Tip packet correspondingto the NV_PCK.

VOBU_S_μM (presentation time information for the video field presentedfirst in the VOBU) can be calculated from the FVFPST of the Tip packetcorresponding to the NV_PCK.

VOBU_E_PTM (time information when presentation of video data in the VOBUends) can be obtained from the presentation time information written tothe next entry in the access map, or it can be generated by analyzingthe video stream of the VOBU and calculating the time at which videopresentation ends.

VOBU_SE_E_PTM (time information when presentation of video data in theVOBU ends according to the sequence_end_code field) is filled with“0x00000000” in all VOBUs before the last VOBU, because thesequence_end_code is only permitted in the last VOBU and the middle VOBUtherefore do not contain the sequence_end_code. VOBU_SE_E_PTM is set tothe same value as in VOBU_E_PTM in only last NV_PCK havingsequence_end_code in the last VOBU

C_ELTM is the time difference between the presentation time of the firstvideo frame presented in a cell storing NV_PCK and the video frame firstpresented in the VOBU, and must be expressed with frame precision.C_ELTM can be calculated as needed by the data recording apparatusduring the conversion process using the FVFPST of the corresponding Tippacket and the presentation time information of the video framepresented at the beginning of a CELL.

NV_PCK PCI data can thus be generated as needed by VOBU unit duringconversion as described above.

FIG. 53 shows the DSI structure of the NV_PCK. As shown in FIG. 53 theDSI data field includes: DSI_GI (Data Search Information GeneralInformation) storing general DSI information; SML_PBI (Seamless PlaybackInformation) storing recording address and playback information neededfor seamless presentation between VOBs; SML_AGLI (Angle Information forseamless) storing location information needed for seamless presentationbetween different angles and so on; VOBU_SRI (VOB Unit SearchInformation) storing the recording address of VOBU adjacent to aparticular VOBU; and SYNCI (Synchronous Information) enablingsynchronous presentation of video with audio/subpictures.

When converted from a Constrained SESF, SML_AGLI stores informationindicating invalid.

FIG. 54 shows the DSI_GI structure of an NV_PCK. Note that calculationmethods are described below only for those fields that must becalculated during conversion from a Constrained SESF.

NV_PCK_SCR (the SCR of the NV_PCK) is deduced from the SCR deduced fromthe ATS of the Constrained SESF by the method described further below.

NV_PCK_LBN (relative address of the NV_PCK in the VOBS file) is obtainedin the same manner as the PCI data.

VOBU_EA (relative address from the NV_PCK to the last pack in the VOBU)can be calculated from the access map. As described above, the number ofpackets not belonging to a Multiplexing Unit between two consecutive Tippackets is known (fixed). Therefore, the number of TS packets to thenext entry (the next Tip packet) can be calculated from the access map.The number of TS packets in that TS packet not belonging to aMultiplexing Unit then subtracted, and the difference is then divided by11 to determine the number of packs formed after the NV_PCK. The numberof packs generated after conversion can be counted and written to theNV_PCK derived from the last Tip packet or to all NV_PCK.

VOBU_(—)1STREF_EA (relative address in the VOBU from NV_PCK to the lastpack in the first referenced picture), VOBU_(—)2NDREF_EA (relativeaddress in the VOBU from NV_PCK to the last pack in the secondreferenced picture), and VOBU_(—)3RDREF_BA (relative address in the VOBUfrom NV_PCK to the last pack in the third referenced picture) can bedetermined without analyzing to the video stream layer if the Tip packetPES_info field is referenced during TS2PS conversion.

PES_info stores the picture_coding_type indicating the type of encodingapplied to the picture stored in each video PES packet. A PES packetwith a picture_coding_type of 01b or 10b stores a reference picture asdefined in the DVD Video standard.

It is therefore possible to reference the PES_info field during TS2PSconversion to determine if the PES packet being converted stores areference picture, and the pack in which said converted PES packet endsbecomes the last pack of the reference picture.

Because the last pack of a reference picture can be identified duringconversion, it is also possible while generating the VOBU to determinein which pack the first, second, and third reference pictures end, andwrite a relative address to the end of each said picture in theVOBU_(—)1STREF_EA, VOBU_(—)2NDREF_EA, and VOBU_(—)3RDREF_EA fields ofthe first NV_PCK in the VOBU.

Alternatively, during conversion of SESF Capsule, with reference toPTS_DTS_flags of PES packet storing video data, storage of the referencepicture may be determined serially to calculate these values. Forexample, if PTS_DTS_flags is 11b, the reference picture is determined tobe stored, while if PTS_DTS_flags is 10 b, the non-reference picture isdetermined to be stored.

VOBU_VOB_IDN (the ID number of the VOB to which the VOBU belongs) shouldbe obtainable by the data recording apparatus during conversion. Whenone Constrained SESF is being converted, VOB segmentation due to thestream conditions, such as an attribute change, is prevented and thesame ID number can be assigned by setting the Constrained SESFencode_condition to 11b.

Like VOBU_VOB_IDN, VOBU_C_IDN (the ID number of the CELL to which theVOBU belongs) is set by the data recording apparatus during conversion,and is not related to the stream. If the CELL is intentionally segmentedbased on the PGC information or other management information for theConstrained SESF, a number determined by the segmentation is simplyassigned.

C_ELTM is the time difference between the presentation time of the firstvideo frame presented in a cell storing NV_PCK and the video frame firstpresented in the VOBU, and must be expressed with frame precision.C_ELTM is the same as the C_ELTM written to the PCI data.

Each field of the DSI_GI field in the NV_PCK can thus be continuouslygenerated by VOBU unit during conversion as described above.

FIG. 55 shows the structure of the SML_PBI field in NV_PCK. Note thatcalculation methods are described below only for those fields that mustbe calculated during conversion from a Constrained SESF.

VOB_V_S_PTM (presentation time of the first video frame presented in theVOB to which NV_PCK belongs) can be determined from the FVFPST of thefirst Tip packet.

VOB_V_E_PTM (video presentation end time in the VOB to which NV_PCKbelongs) can be set anytime by analyzing the stream after the last Tippacket in the part of the Constrained SESF selected for conversionbefore the actual TS2PS conversion and obtaining the end presentationtime of video data.

It is thus possible to calculate the fields of SML_PBI of NV_PCK beforeconversion. It is enough to use that value during the conversion.

As noted above VOBU_SRI can be calculated using the access map, andfurther description thereof is thus omitted here.

Furthermore, VOBU SRI is written completely within each cell and thuscannot be determined if the cell is not defined. Therefore, a recorderthat records in the DVD Video format in real-time cannot create cells atany desired interval and thus suffers from degraded editing and playbackperformance. When converting from a Constrained SESF, however, cells canbe defined as periods specified by the user and converted using themethod described above, chapters can be created as intended by the user,and a play list that starts playback from a user-defined point can becreated conforming to the DVD Video format.

FIG. 56 shows the structure of the SYNCI field of NV_PCK. Note thatcalculation methods are described below only for those fields that mustbe calculated during conversion from a Constrained SESF.

A_SYNCA0 is the relative address of a pack storing a primary audio packand storing the audio frame presented simultaneously to or immediatelyafter VOBU_S_PTM. It can be determined using the PES_info in the Tippacket without analyzing the stream during TS2PS conversion.

Whether a PES packet stores primary audio can be determined by readingthe stream_identifier of the PES_info, and at the next sync_presentationflag it is possible to determine whether there is an audio framepresented simultaneously to or immediately after VOBU_S_PTM in the audioframe contained in the PES packet. Therefore, if the PES packet containsprimary audio and the sync_presentation_flag=1b, the address from theNV_PCK to the pack storing the PES packet can be written during TS2PSconversion.

It should be noted that there is no guarantee that thesync_presentation_flag=1b will be set in one audio pack of the VOBU. Ifthe encoder multiplexes the audio first, the audio pack presentedsimultaneously to or immediately after VOBU_S_PTM of the VOBU could bestored in the preceding or the following VOBU.

The value set to the A_SYNCA0 field must therefore be determined duringconversion with a correct understanding of the sequential relationshipbetween the PES packet of the primary audio (thesync_presentation_flag=1b) and the subsequently generated NV_PCK.

To eliminate this process the Constrained SESF can be system encoded sothat the audio data presented simultaneously to or just after the FVFPSTwritten to the first Tip packet in the SESF capsule is also stored inthe same SESF capsule.

By using these definitions a process for detecting audio datasynchronized to VOBU_S_PTM (FVFPST) outside the VOBU (SESF capsule) canbe eliminated.

A_SYNCA1 is the relative address of a pack storing a secondary audio andstoring the audio frame presented simultaneously to or immediately afterVOBU_S_PTM, and can be determined using the same method as A_SYNCA0.

Except for A_SYNCA, it is thus possible to sequentially generate DSIdata of NV_PCK by VOBU unit during conversion.

An example of NV_PCK generation is as shown in FIG. 84.

<DVD Video Recording Format>

Field settings during conversion to the DVD Video Recording (VR) streamformat are described next below.

The DVD VR stream is described briefly below. Note that the DVD VRstream format is described in detail in “DVD Specifications forRewritable/Re-recordable Discs, Part 3, VIDEO RECORDING.”

FIG. 57 shows the stream structure of the DVD VR format. As shown hereeach stream includes multiple VOBs, and each VOB contains an integernumber of VOBUs. A VOBU includes an integer number of packs, startingwith an RDI_PCK followed by a video pack (V_PCK) and an audio pack(A_PCK). Unlike a normal pack, the RDI_PCK contains presentation andcopy control information, and manufacturer-specific information. Thefields contained in the RDI_PCK are described below together with howthe field values are determined.

As shown in the figure, the RDI_PCK payload data (RDI Unit) includes:RDI_GI (Real-time Data Information General Information) storing generalinformation of RDI, DCI_CCI (Display Control Information and CopyControl Information) storing information used for display and copycontrol, and MNFI (Manufacturer's Information) storingmanufacturer-specific information.

The RDI_GI field contains a VOBU_S_PTM field. Only this field isvariable and the other field values are fixed.

VOBU_S_PTM has the same format as the FVFPST written to thecorresponding Tip packet in the transport stream before conversion, andthe FVFPST value can therefore be simply copied to the VOBU_S_PTM field.

DCI_CCI has the same format as the display_and_copy_info field of theTip packet, and the display_and_copy_info value can therefore be simplycopied to the DCI_CCI field.

A specific manufacturer ID is allocated only when the maker_ID writtento the Tip packet is identical to the manufacturer ID of the datarecording apparatus, and the manufacturer-specific information is copiedto the MNFI field. However, if the maker_ID in the Tip packet is the IDfor a different manufacturer, or the maker_ID is invalid, the RDI packcan be generated by writing invalid data to the MNFI field.

It is possible that part of the data written to the Tip packet isinvalid. In this case a flag (an invalidation flag) indicating thatthere is invalid data in the Tip packet should be set. If thisinvalidation flag is set to ON, the flag must be updated after updatingthe invalid data in the Tip packet to the most recent data.

As an example of this, considered can be a case where the most recentCCI data and a TS packet CCI data invalidation flag are present in theATS (4B) of each TS packet.

In this case it is necessary to determine if the invalidation flag isset during TS2PS conversion. If it is, it is necessary to convert to anRDI_PCK using data updating the CCI data in the display_and_copy_infofield with the CCI flag of the ATS.

RDI_PCK can thus be sequentially generated using only the correspondingTip packet (and ATS thereof).

FIG. 58 is a flow chart of the above RDI_PCK generation process.

In a RDI_PCK (or NV_PCK), the system header includes fixed-value fields.Details of the system header are shown in FIG. 61. The packet header andprivate header stored to the RDI_PCK are shown in FIGS. 62A and 62B,respectively. Because these headers include fixed-value fields as shownin the figures, they can be easily generated.

FIG. 59 is a flow chart of a process for generating PS packs from TSpackets (Multiplexing Unit) storing AV data.

As shown in the figure, TS packets of a Constrained SESF storing AV dataare converted using one Multiplexing Unit as the unit of processing to 2KB packs of an MPEG_PS storing AV data. This is further described belowfollowing the steps of this process.

(Step S4200): One TS packet is read from the conversion starting pointof the Constrained SESF stream.

(Step S4201): Whether the read TS packet stores AV data and is the firstTS packet in a Multiplexing Unit is determined.

Whether AV data is stored is determined by reading the PID value of theTS packet declared in the PMT to store AV data. The TS packet isdetermined to be at the beginning of a Multiplexing Unit when thepreceding TS packet is a Tip packet, PSI/SI packet, or PCR packet andthe TS packet following immediately thereafter stores AV data. Because aTip packet is expected at a conversion starting point, whether it is atthe beginning of a Multiplexing Unit can be determined by sequentiallyreading the TS packet (that is, the first TS packet storing AV dataimmediately after a Tip packet is always at the beginning of aMultiplexing Unit). If the TS packet is determined to not be at thebeginning of a Multiplexing Unit, or if conversion does not start from aTip packet and the determination cannot be made, control loops back tostep S4200 to read the next TS packet. Control moves to the next stepafter the beginning of a Multiplexing Unit is found.

(Step S4202): Using the ATS assigned to the TS packet at the beginningof the Multiplexing Unit, the time (calculated_PCR) at which the MPEG_PSpack to which the TS packet is converted will be input to the decoder iscalculated. The PCR is calculated as described above. Once the PCR iscalculated the SCR can be determined by the method described above, andthe pack header shown in FIG. 60 is completed. This is because exceptfor the SCR only fixed values are permitted in the pack header.

(Step S4203): The packet header and private header are determined.

The packet header is created based on the PES packet header of theConstrained SESF. The form of the packet header must satisfy the fieldvalues shown in FIG. 63. This is because conversion from the ConstrainedSESF will not be determined uniformly if field values that will changethe header length are not set, and buffer management may be affected.Field not shown here are fixed values and are therefore not listed.

Individual field values of the PES packet header are determinedspecifically with the Constrained SESF in order to minimize theprocessing required for PES packet header (MPEG_TS) to packet header(MPEG_PS) conversion.

If the PES packet is large relative compared to the size of one pack,one PES packet will be converted to plural packs. In this case revisionsto the packet headers of the second and subsequent packs include settingPTS_DTS_flags in the first packet header generated from the PES packetto 00b, the PES_extension_flag to 0b, adjusting the stuffing_bytelength, and correcting PES_header_data_length.

The private header is required when a non-MPEG stream is stored, and istherefore required in packs storing NV_PCK, RDI_PCK, AC-3, or LPCM.

FIG. 64 shows the private header of an AC-3. Of the fields shown in thefigure, only the number_of_frame_headers field requires calculatingduring TS2PS conversion according to the Constrained SESF MultiplexingUnit definition. Because this field specifies the number of AC-3 audioframes stored in the pack, the field value can be easily calculated fromthe PES_packet_length for fixed-rate AC-3, for example, because the bytelength of one audio frame is calculable from the bit rate and the valueis a fixed length.

It should be noted that the PES_header_data_length of the PES packetheader of a Constrained SESF is stuffed with an extra 4 bytes by theAC-3 private header (4 bytes). (See FIG. 44.) By thus estimating beforeconversion the header length after conversion and shifting the payloadposition, sequential process in units of TS packet can be easily done.

As described above, the first packet header is generated by correcting apart of the PES packet header, the second and later packet headers isgenerated by correcting a part of the first packet header, and theprivate header is inserted only for streams not complying with MPEGstandard. The packet header and private header can thus be generated.

(Step S4204): Once the private header is generated, the PS pack payloadis filled from the beginning thereof by simply copying data from the TSpacket payload.

(Steps S4205 to S4207): These steps simply repeat until the MultiplexingUnit (11 TS packets) is completed. However, because it is possible thata Null packet has been inserted, TS packet payload data is copied whilethe Null packet PID (0x1FFF) is detected.

Preferably it is defined that only the TS packet storing the last dataof the PES packet has an adaptation field. This makes reading thepayload data easier because TS packets other than TS packet storing thelast data of PES packet in Constrained SESF always store 184 bytes ofpayload data.

(Step S4208): When all Multiplexing Unit payload data has been copied,the byte length of the resulting pack is calculated to confirm if a bytelength is 2048 bytes. Pack generation ends if there are 2048 bytes. Ifthe pack contains less than 2048 bytes, control steps to S4209.

(Step S4209): If the pack does not contain 2048 bytes, a padding packetis added to the end of the payload to a total of 2048 bytes.

The conversion process thus proceeds from a Multiplexing Unit storing AVdata. This process repeats only if a Multiplexing Unit is detected untilprocessing the part of the Constrained SESF selected for conversionends.

The result of the above conversion process applied to packs of differenttypes is described next below.

<Conversion to a Video Pack (V_PCK)>

FIGS. 65A and 65B show the conversion from a Constrained SESF toMPEG_PS. As shown in FIG. 65A, one video PES packet is normally largerthan 2 KB, and is therefore segmented to plural Multiplexing Units andmultiplexed to a Constrained SESF.

Based on the Constrained SESF definition each Multiplexing Unit otherthan the last Multiplexing Unit in a video PES packet is filled with thegreatest possible amount of video PES packet data. Every MultiplexingUnit other than the last Multiplexing Unit therefore stores 2024 bytes(=184×11 bytes) of data.

Using this definition makes it possible to predefine such fields as thePES_packet_length and stuffing_byte of each pack at TS2PS conversion.

The last Multiplexing Unit storing data for one video PES packet mayfill the remaining data capacity with the adaptation field and Nullpackets to form one complete Multiplexing Unit, or store data of thenext PES packet for efficient data transfer (for increasing amount ofdata stored to the converted MPEG-PS pack).

However, in consideration of facility of conversion to DVD, onlyI-picture in SESF capsule is located from the beginning TS packet in theMultiplexing Unit storing the first video data in the SESF capsule.P-picture and B-picture may not be located from the beginning of theMultiplexing Unit as describe above.

As shown in FIGS. 65A and 65B, the following three types of MultiplexingUnits are used to form one video PES packet: the first Multiplexing Unitstoring the first data in the PES packet (MU #1 in the figures);Multiplexing Units (MU #n where n=2, 3, . . . N−1) storing data in themiddle of the PES packet; and the Multiplexing Unit (MU #N) storing thelast PES packet data.

The structure of the packs corresponding to these Multiplexing Unittypes in the MPEG_PS stream resulting from TS2PS conversion is shown inFIG. 65B.

The pack converted from MU #1 always contains at least 10 bytes of emptyspace, and padding packets are therefore inserted at the end when thepack is generated.

This is because the DVD format specifies that stuffing bytes (last fieldof the packet header) are added to a total 2048 bytes when there is aspace of 7 bytes or less in the pack, and padding packets are added ifthe space is 8 bytes or larger.

One stuffing byte is added to the packs converted from MU #n to completeeach pack.

The pack converted from MU #N normally has a space of 8 bytes or larger,and a padding packet is therefore inserted.

<Conversion to an Audio Pack (A_PCK)>

FIGS. 66A and 66B shows conversion from Constrained SESF to MPEG_PS. Asshown in FIG. 66A, one audio PES packet (storing one or more audioframes) is smaller than one Multiplexing Unit.

Because one audio PES packet will fit in one Multiplexing Unit, complexconversion is not required as it is for a video PES packet. Morespecifically, packs to which padding packets are added should always begenerated as shown in FIG. 66B.

Furthermore, because PES_packet_length does not change with TS2PSconversion, only simple calculations are required for conversion. Theseinclude appropriately setting the stream_id when converting MPEG-1Audio, and generating the AC-3 private header.

As also shown in the figure, buffer management can be simplified byminimizing the audio data transfer time, which is the greatest factorcomplicating system encoding a Constrained SESF.

Because video data and other PSI/SI packets cannot be transferred whenaudio Multiplexing Units are being transferred, the overall transferrate drops (i.e., image quality drops), and as the transfer timeincreases the video data must be transferred that much earlier on thetransport stream (thus complicating system encoding). The audioMultiplexing Unit transfer time is therefore preferably as short aspossible.

In other words, transferring the audio Multiplexing Unit in a shortertime means increasing the audio transfer rate. This is connected toreducing the difference between the allowed audio input rates, which isa major difference between the T_STD and P_STD. A major benefit of thisis to also simplify generating a Constrained SESF, which must conform toboth decoder models.

FIG. 67 shows the audio bit rates allowed in a Constrained SESF and themaximum payload length stored to one audio PES packet when AC-3 andMPEG-1 Audio is stored at each bit rate. Because data longer than theshown byte lengths will not fit in one audio PES packet, padding packetsare inserted.

(Constraints in PES Packet)

Integer number of PES packets including integer number of audio framesmay be stored to integer number of Multiplexing Units so as to increaseamount of data which can be stored in converted MPEG-PS pack, thusachieving efficiency multiplexing. However in this case, a problem mayoccur on PTS calculation during the conversion.

DVD standard specifies that PTS of the first one of audio frames whichstart in PES packet for audio should be described as PTS in a packetheader of a PES packet for audio.

In TS2PS conversion, there may be a case in that an audio frame at ahead of PES packet after conversion to MPEG-PS (DVD) does not conformwith an audio frame at a head of PES packet multiplexed with theconstrained SESF before conversion. Accordingly, in the presentinvention. the multiplexing process is performed according to theconstrained SESF so that the first one of audio frames in PES packet ofa pack of MPEG-PS after conversion always includes PTS. Thus it is notnecessary to calculate and obtain PTS newly in TS2PS conversion.

Accordingly, it is effective to arrange that the first one of completeaudio frames in the Multiplexing Unit is the first one (that is, theaudio frame with PTS inevitably recorded) of audio frames in a payloadof PES packet in Multiplexing Unit. Therefore, the constrained SESFaccording to the present invention defines that the first one ofcomplete audio frames in the Multiplexing Unit is the first one of audioframes in a payload of PES packet in the Multiplexing Unit. Thisdefinition may also be defined so that an audio frame of which beginningbyte starts first in the Multiplexing Unit is the first audio frame in apayload of PES packet in the Multiplexing Unit. The constraint by thisdefinition is one of constraints of the constrained SESF, and thus it ispossible to judge if the definition is satisfied by referring toencode_condition flag.

FIG. 85 is a figure showing MPEG-TS which is formatted in theconstrained SESF satisfying the above definition and MPEG-PS which isconverted therefrom.

PES packet header of PES packet 411, 412 or 413 includes PTS value(PTS#1, PTS#5 or PTS#8) for the first audio frame (AF#1, AF#5 or AF#8)in audio frames included in each PES packet 411, 412 or 413.

The first Multiplexing Unit (401) includes all data for PES packet 411and a part of data for PES packet 412.

The first complete audio frame in the first Multiplexing Unit (401) isaudio frame #1 which is the first audio frame in the payload of PESpacket 411 and thus satisfies the above definition. Regarding the secondMultiplexing Unit (402), the first complete audio frame in the secondMultiplexing Unit (402) is audio frame #8 which is the first audio framein the payload of PES packet 413 and thus satisfies the abovedefinition. It is noted that although the second Multiplexing Unit (402)includes a latter half of audio frame #7 immediately after PES packetheader, the latter half of audio frame #7 is a part of audio frame butis not a complete audio frame. Therefore this is not a condition usedfor considering the above definition.

PES packet header of PES packet 411 included in the first MultiplexingUnit (401) includes PTS value (PTS#1) of the first audio frame #1 ofaudio frames (AF) following the PES packet header. The secondMultiplexing Unit (402) includes PTS value (PTS#8) of the first completeaudio frame #8 in audio frames (AF) following the second MultiplexingUnit.

When converting the second Multiplexing Unit (402) to MPEG-PS, PTS valuestored in PES packet header included in Multiplexing Unit (402), a valueof PTS value (PTS#8) stored in PES packet header included in theMultiplexing Unit (402) is copied as it is to PES packet header in thedestination MPEG-PS. Thus it is enough to copy PTS value in PS2TSconversion, thereby simplifying the process.

Next description is made to a case in that PES packet includes videodata. As one of constraints of constrained SESF regarding PES packetincluding video data, it may be defined that PES packet includingI-picture starts from a head of the Multiplexing Unit.

FIG. 86 shows an example satisfying the above definition. In FIG. 86,PES packet 416 includes I-picture, and PES packet header of the PESpacket stores PTS value (PTS#2) of I-picture. PES packet 416 is locatedat a head of the Multiplexing Unit (404).

In packs of the converted MPEG-PS, PTS value (PTS#2) stored in PESpacket header 421 points out I-picture immediately after the PES packetheader 421. The Multiplexing Unit (403) stores P-picture included in thepayload of PES packet 415. The remaining portion of the MultiplexingUnit is filled with NULL packets to align I-picture to the nextMultiplexing Unit (404).

When the Multiplexing Unit (404) is converted to MPEG-PS, a value(PTS#2) of PES packet header in the Multiplexing Unit (404) is copied toPES packet header 421 of MPEG-PS pack. Hence, it is enough to just copyPTS but it is not necessary to calculate PTS, thus simplifying theprocess.

<TS2PS Conversion Process>

The TS2PS conversion process is detailed next below with reference toflow charts of FIG. 68 to FIG. 81.

FIG. 68 is a flow chart of the main TS2PS conversion process. Thisprocess starts when a user inputs a TS2PS conversion request. The datarecording apparatus then seeks the SESF capsule from which conversionstarts (S81) and determines if the SESF capsule to be processed ispresent (S12). If it is not, the process ends. If the SESF capsule ispresent, an initialization process (S13) and capsule unit process (S14)are run.

The initialization process (S13) is described with reference to the flowchart in FIG. 69. This process sets and initializes the variables andother parameters used in the following process.

Whether a Tip packet has been read is first determined (S21). If a Tippacket has not yet been read, a Tip packet is read (S22). The ATS valueof the read Tip packet is then set to variable ATSTip (S23), the PCRvalue of Tip packet is set to variable PCRTip (S24). Variable MU_numspecifying the number of the Multiplexing Unit being processed is set to0 (S25), and variable WA indicating how many times an ATS overflowoccurred is set to 0 (S26).

The capsule unit process (S14) is described with reference to the flowchart in FIG. 70. This process starts by reading a TS packet (S31) andthen detecting if the read TS packet is a Tip packet (S32). Processingends if it is a Tip packet. If not a Tip packet, it is determinedwhether the read TS packet contains an audio packet or video packet(S33). If the read TS packet does not contain an audio packet or videopacket, control loops back to step S31, and TS packets are sequentiallyread until the read TS packet is an audio packet or video packet (S31 toS33 repeat).

When the read packet is an audio or video TS packet, the next 10 TSpackets are also read (S34). MU_num is then incremented (S35). The ATSvalue of the first TS packet in the Multiplexing Unit is stored tovariable ATS (MU_num) (S36). The byte length of the payload data in thePES packet stored to the Multiplexing Unit is set to payload_len (S37).The pack unit process is then run (S38).

As shown in the flow chart in FIG. 71, the pack unit process includes anSCR calculation process (S41), pack header process (S42), packet headerprocess (S43), payload process (S44), and padding packet process (S45).These processes are described below.

The SCR calculation process is described with reference to the flowchart in FIG. 72.

This process determines the SCR value of the pack. The first step is todetermine whether the Multiplexing Unit is the first Multiplexing Unitin the SESF capsule by referencing variable MU_num (S51). If it is, thevalue of ATSTip is set to variable ATS[0] and the value of variablePCRTip is set to variable SCR[0](S52-S53).

ATS[MU_num] and ATS [MU_num-1] are then compared (S55). The ATS value ofthe first packet in the Multiplexing Unit is stored to ATS[i], and thisATS value indicates the relative transfer timing referenced to aparticular packet. Therefore, the ATS value of each subsequent packet isnormally greater than the ATS value of the previous packet. However,because the ATS is generally limited to a finite value expressible with30 bits, ATS overflow can occur. In this case the ATS value of a certainpacket may be smaller than that of the preceding packet. Step S54monitors this reversal of ATS values to determine when an ATS overflowoccurs. If ATS[MU_num] is not greater than ATS[MU_num-1], that is, if anATS overflow occurred, variable WA is incremented (S55).

The greater one of SCR[MU_num-1]+T and (PCRTIP ATS[MU_num]−ATSTip+WA×BS)is then set to SCR[MU_num] (S56).

The pack header process is described with reference to the flow chart inFIG. 73.

This process edits the pack header data in the data structure shown inFIG. 60. The remainder of the SCR divided by 300 is first inserted toSCR_extension (S61), and the quotient is set to SCR_base (S62). Theprogram_mux_rate is set to “0x6270” (S63), and pack_stuffing_length to“000b” (S64). Other fields are edited appropriately to complete the packheader data (S65).

The packet header process is described with reference to the flow chartin FIG. 74.

This process starts by running a stream ID process for setting thestream ID (S71). Whether Multiplexing Unit contains video data is thendetermined (S72). When Multiplexing Unit includes video data, it isdetermined whether the beginning TS packet in Multiplexing Unit includesPES packet header (S73). If the first TS packet of the Multiplexing Unitcontains a PES packet header, a video PES packet leading process is run(S74), and a PES packet non-leading process is otherwise run (S75).Whether the first TS packet of the Multiplexing Unit contains a PESpacket header can be determined by reading thepayload_unit_start_indicator field of the TS packet header, or bydirectly detecting if a PES packet header start code is stored.

On the contrary, when Multiplexing Unit does not include video data, itis judged if Multiplexing Unit includes PES packet header (S76). WhenMultiplexing Unit includes PES packet header, audio PES packet leadingprocess is performed (S77), otherwise audio PES packet non-leadingprocess is performed (S78).

The stream ID process is described with reference to the flow chart inFIG. 75.

This process sets the value of the stream_id field. If the type of thestream being processed is “MPEG-2 Video”, the stream_id is set to “0xE0”(S81, S82). If the stream type is “AC-3 audio”, the stream_id is set to“0xBD” (S83, S84). If the stream type is “MPEG-1 Audio” and “primaryaudio”, the stream_id is set to “0xC0” (S85, S86, S87). If the streamtype is “MPEG-1 Audio” and “secondary audio”, the stream_id is set to“0xC1” (S85, S88, S89).

The PES packet leading process is described with reference to the flowchart in FIG. 76.

The structure of a PES packet according to the MPEG standard is shown indetail in FIG. 81. This process edits the PES packet fields according tothe structure shown in FIG. 83.

First, PES packet header which is the same as the first PES packetheader stored in TS packet at a head of Multiplexing Unit is generatedas PES packet header of the converted MPEG-PS (S91). Next,PES_packet_length is set to the value determined by the followingequation (S92).

PES_packet_length=(3+PES_header_data_length)+payload_(—) len

Then, it is determined whether PES_extension_flag is “1” (S93). WhenPES_extension_flag is “1”, the 3 bytes from PES_private_data_flag toP_STD_buffer_size are overwritten with a predetermined value (0x1E60E8)(S94).

The video PES packet non-leading process is described with reference tothe flow chart in FIG. 77.

The PES packet header is set to a provisional value(0x000001E007EC800001FF) (S111). It is determined whether a value of(2025−payload_len) is between 1 and 8 (S112).

If the value of (2025−payload_len) is not less than 8, the control goesto Step S116.

If the value of (2025−payload_len) is between 1 and 8,PES_header_data_length is set to (2025−payload_len) (S113), andPES_packet_length is set to a value determined by the following equation(S114).

PES_packet_length=(3+PES_header_data_length)+payload_(—) len

Then, stuffing_byte is filled with stuffing bytes with a length of(2024−payload_len) bytes (S115), and the control goes to Step S116.

In Step S116, it is determined whether the value of (2025−payload_len)is not less than 8. If it is not less than 8, PES_header_data_length isset to 0 (S117), and PES_packet_length is set to a value determined bythe following equation (S118).

PES_packet_length=3+payload_(—) len

Then, one byte of stuffing byte is removed from stuffing_byte (S119).

The audio PES packet leading process is described with reference to FIG.78.

First, PES packet header which is the same as PES packet headerappearing first in Multiplexing Unit is generated as PES packet headerof the converted MPEG-PS (S181). Next, PES_packet_length is set to thevalue determined by the following equation (S182).

PES_packet_length=(3+PES_header_data_length)+payload_(—) len

Then, it is determined whether PES_extension_flag is “1” (S183). IfPES_extension_flag is “1”, P_STD_buffer_flag is set to 1 (S184). Then itis determined whether the audio data is AC-3 audio (S185). If the audiodata is AC-3 audio, the two bytes following PES_extension_flag_(—)2 isset to a predetermined value (0x603A) (S186). If the audio data is notAC-3 audio, the two bytes following PES_extension_flag_(—)2 is set to apredetermined value (0x4020) (S187).

The audio PES packet non-leading process is described with reference toFIG. 79.

It is determined whether stream_id is “0xBD”, that is, whether the audiodata is AC-3 audio (S191). If stream_id is “0xBD”, PES packet header isset to a provisional value (0x000001BD0000800004FFFFFFFF) (S192). ThenPES_packet_length is set to a value determined by the following equation(S193).

PES_packet_length=7+payload_(—) len

If stream_id is not “0xBD”, It is determined whether stream_id is“0xC0”, that is, whether the audio data is MPEG-1 primary audio (S194).If the audio data is MPEG-1 primary audio, PES packet header is set to aprovisional value (0x000001C00000800000) (S195). If not MPEG-1 primaryaudio, PES packet header is set to a provisional value(0x000001C0000800000) (S196). Then PES_packet_length is set to a valuedetermined by the following equation (S197).

PES_packet_length=3+payload_(—) len

The payload process is described with reference to the flow chart inFIG. 80.

Variable i is set first (S121), and the payload data of the PES packetstored to the i-th TS packet is read (S122). The payload data of the PESpacket stored to the i-th TS packet is then added to the payload of thepack (S123) and variable i is incremented (S124). These steps repeatuntil variable i is greater than 12 (S125). That is, this processrepeats until all TS packets contained in one Multiplexing Unit areprocessed (S122 to S125).

The padding packet process is described with reference to the flow chartin FIG. 81.

Whether the PES_packet_length is set to 2028 is determined (S131). IfPES_packet_length is not 2028, PES_packet_length of the padding packetis set to {(2028−PES_packet_length)−6} (S132), and padding packets areadded after the payload (S133).

PTS described in PES packet of MPEG-2 converted in the manner asexplained above can be set with reference to PES packet header appearingfirst in Multiplexing Unit (see FIGS. 85 and 86).

Furthermore, because the PES_packet_length indicating the length of thevideo PES packet is set to 0 above, there is a problem that thePES_packet_length of the packet header after conversion to a pack cannotbe determined until data writing to the pack completes. ThePES_packet_length for each video PES packet in the SESF capsule can bewritten to the Tip packet. The PES_packet_length can therefore bedetermined by sequential processing of TS packet units, and conversioncan proceed even more quickly.

Furthermore, the pack header (SCR) is described above as calculatedduring TS2PS conversion, but the pack header can be previously stored tothe PES packet header stored in the MPEG_TS. For example, the packheader after TS2PS conversion could be stored to the PES packet headerwith a pack_header_field_flag in the PES packet header set to 1 b. Thedata stored to the pack storing the pack header includes the data storedin packets from the TS packet to a TS packet determined by a specificrule (for example, a specific number to TS packets).

(Constraint of Video Picture in Continuous STC Section)

As shown in FIG. 87A, in a continuous STC (system target decoderreference time clock) section, a video picture (Pf) which is presentedfirst in the first complete SESF capsule may be a top field, and a videopicture (Pl) which is presented last in the last complete SESF capsulemay be a bottom field. FIG. 87B shows a case not satisfying this rule,in which a video picture (Pf) which is presented first in the firstcomplete SESF capsule is a bottom field, while a video picture (Pl)which is presented last in the last complete SESF capsule is a topfield. The reason why a manner of presenting video picture isconstrained as described above in a continuous section of a completeSESF capsule is because re-encoding of video stream on conversion ofDVD-Video into VOB (if no edition of recorded stream occurs) can beprevented. This is because DVD standard requires that video data in oneVOB is reproduced starting at the top field and ending at the bottomfield.

The above constraint is one of constraints of the constrained SESF, andthus it is possible to judge if the above constraint is satisfied byreferring to encode_condition flag. That is, reference of this flagmakes it possible to judge that, in a continuous STC section, a videopicture which is presented first in the first complete SESF capsule is atop field and a video picture which is presented last in the lastcomplete SESF capsule is a bottom field.

FIG. 88 is a flowchart of recording process according to the constrainedSESF provided with the above constraint.

First, generation of a continuous STC is started (S201). Next, a valueof preset encode_condition is acquired (S202). The value ofencode_condition is set in advance at an initial setting for user andrecorder, and so on. It is determined whether encode_condition is “11b”(S203). When encode_condition is “11b” (recording in DVD-Video mode), itis determined whether the first complete SESF Capsule is being encoded(S208). When the first complete SESF Capsule is being encoded, encodingprocess is done so that a picture to be presented first in the firstcomplete SESF Capsule is a top field (S209). Subsequently, the data isencoded as the constrained SESF to satisfy requirements forencode_condition which is “11b” (S210).

When encode_condition is “01b” (recording in DVD-Video Recording mode),the data is encoded as the constrained SESF to satisfy requirements forencode_condition which is “10b” (S204).

Subsequently, time map information is updated every time the SESFCapsule is completed (S205). It is determined whether the recording ends(S206). When the recording ends, an end recording process is performed(S207). Until the recording ends, the above steps S203 to S205 arerepeated.

The end recording process is described with reference to FIG. 89.

It is determined whether encode_condition is “11b” (S211). Whenencode_condition is “11b”, it is determined whether a picture to bepresented last in the last complete SESF Capsule is a bottom picture(S212). When the picture is not a bottom picture, encoding process isperformed so that new SESF is generated or SESF which is being encodedis completed and that the picture presented last is a bottom picture(S213).

When encode_condition is not “11b”, the last SESF capsule to satisfyrequirements for encode_condition which is “01b” is generated (encodingis terminated) (S214).

Subsequently, time map information is completed and recorded in therecording medium (S215).

<Seamless Connection>

The constraints on seamlessly connecting two VOB (system streams) in aConstrained SESF are described next with reference to FIG. 90. Aseamless connection is a connection enabling two separate VOBs (systemstreams) to be reproduced continuously in time. FIG. 90 shows seamlesslyconnecting VOB #1 and VOB #2 specified by Cell #1 and Cell #2,respectively. Various seamless connection methods are known from theliterature (see, for example, U.S. Pat. No. 5,923,869).

The Blu-Ray Disc (BD) standard, that is, a standard for next-generationrecording media, describes, for each Cell in a PGC, the connection tothe chronologically preceding Cell. Cell #2 in FIG. 90, for example,contains information (“connection information”) describing theconnection to the Cell (Cell #1) that is reproduced before Cell #2. Thisconnection information is called the connection_condition, and is storedin the VOB management information (VOBI).

The connection_condition can be set to the following values.

1: a normal non-seamless connection

2: a normal non-seamless connection

3: seamless connection (through a Bridge-VOB)

4: seamless connection (not through a Bridge-VOB)

If the connection_condition is 3 or 4, a particular Cell meets theconditions for a seamless connection to the preceding Cell. Theconnection_condition of Cell #1 is 1 in the example shown in FIG. 90. Itmeans that Cell #1 is not seamlessly connected to the preceding Cell. Onthe contrary, the connection_condition of Cell #2 is 4, thus it meansthat Cell #2 is seamlessly connected to the preceding Cell #1.

If the encode_condition=01b or 11b, that is, if VOB #1 and VOB #2 are aConstrained SESF, PGC #1 which is composed of Cell #1 and Cell #2seamlessly reproduced in a BD standard can preferably be directlyconverted at high speed (TS2PS conversion) even when converted to a BDstandard.

To enable this, it is required that a target portion for TS2PSconversion should include a complete SESF Capsule. That is, at least,the beginning of an SESF Capsule must come immediately after theseamless connection. In other words, as shown in FIG. 90, the streamimmediately following seamless connection X must start with a Tip packet303, which is a packet denoting the start of a Capsule. Starting thebeginning of a Capsule immediately after a seamless connection pointthus enables video presentation to continue immediately following theseamless connection. Another condition is that a complete SESF Capsulemust end immediately before the seamless connection.

A seamless connection in a Constrained SESF where connection_condition=3is described next with reference to FIG. 91.

At a seamless connection where connection_condition=3, the VOB that isreproduced previously in chronological order and the VOB that isreproduced next are connected through a Bridge-VOB. A Bridge-VOB is aVOB that is produced by extracting the first and second halves of theBridge-VOB from the leading VOB and trailing VOB that are to beseamlessly connected, and then re-encoding the extracted parts to enableseamless presentation. Using a Bridge-VOB for a seamless connection isdescribed, for example, in unexamined U.S. patent application2002-90197.

In FIG. 91, PGC #1 reproduces VOB #1 and VOB #2 through the followingpresentation path. VOB #1 (301) is reproduced from Start_SPN1 toexit_to_Bridge_SPN, Bridge-VOB (304) is then reproduced from beginningto end, and finally VOB #2 (302) is reproduced fromreturn_from_Bridge_SPN to END_SPN (the position of End_PTM2 on the timemap). Start_SPN1, exit_to_Bridge_SPN, and return_from_Bridge_SPN denotea TS packet address. The information is contained in the VOB managementinformation VOBI.

When a Bridge-VOB is used to make a seamless connection, the part of theBridge-VOB immediately following the seamless connection X where thecontent of VOB #1 ends and the content of VOB #2 begins must start witha complete Capsule, that is, must start from a Tip packet 303. Inaddition, a part immediately before the seamless connection must endwith a complete Capsule.

A seamless connection using a Bridge-VOB is described in further detailbelow with reference to FIG. 92. In this example, VOBs havingencode_condition=11b (that is, VOB conforming to a Constrained SESF) areseamlessly connected using a Bridge-VOB, and the seamlessly connectedstream is then converted to the DVD format.

Referring to FIG. 92, VOB#1 (301) includes four Capsules labeled Capsule1-1 to Capsule 1-4, and VOB#2 (302) includes four Capsules labeledCapsule 2-1 to Capsule 2-4. Bridge-VOB 304 includes Capsule 1-3′,Capsule 1-4′, Capsule 2-1′, and Capsule 2-2′. The first half ofBridge-VOB 304, that is, Capsule 1-3′ and Capsule 1-4′, are generatedfrom Capsules 1-3 and 1-4 in VOB 301 before the seamless connection. Thesecond half of Bridge-VOB 304, that is, Capsule 2-1′ and Capsule 2-2′,are generated from Capsules 2-1 and 2-2 in VOB 302 following theseamless connection.

In the BD Standard, a VOB is composed of units called “Aligned Units”. Asingle Aligned Unit contains thirty-two source packets each contains aset of ATS and TS packet, and is 6 KB long.

When a Bridge-VOB is used in the BD Standard, the point from which thepreceding VOB leaves (exit_to_Bridge_SPN) and the point to which thenext VOB enters (return_from_Bridge_SPN) must both be at an Aligned Unitboundary.

Creating a Bridge-VOB from SESF Capsule units (see FIG. 92) instead ofcreating the Bridge-VOB from the middle of a SESF affords bettervideo/audio data alignment and more clearly defines the units for there-encoding process. As a result, pre-aligning the SESF Capsule boundarywith the Aligned Unit boundary in a Constrained SESF is preferable fromthe perspective of connection to the Bridge-VOB. This can be easilyachieved by filling the end of the SESF Capsule to the Aligned Unitboundary with null packets.

A Bridge-VOB 304 which is generated from SESF Capsules aligned at theAligned Unit, specifically Capsule 1-3 and Capsule 1-4 in VOB #1 (301)and Capsule 2-1 and Capsule 2-2 in VOB #2 (302) in this example, has adiscontinuity point on the STC time base and ATS time base betweenCapsule 1-4′ and Capsule 2-1′.

Converting SESF Capsules on a continuous ATS/STC time line is simple asdescribed above, and thus the Capsules immediately before and after theseamless connection in the Bridge-VOB must both be complete SESFCapsules in order to enable TS2PS conversion without losing audio/videodata. This means that in the example shown in FIG. 92, Capsule 1-4′before and Capsule 2-1′ after the seamless connection must be completeSESF Capsules.

Furthermore, according to the condition which is required fromencode_condition=11b of the Bridge-VOB, the last Capsule 2-2′ in theBridge-VOB 304 should have a presentation time of 0.4 to 1.2 sec as thelast complete SESF Capsule. However, when Capsule 2-2′ is converted tothe DVD format, if the presentation time of the converted Capsule 2-2′is greater than 1.0 sec. in the DVD VOB converted from Capsules 2-1′,2-2′, 2-3, and 2-4, compatibility with the DVD standard is poor andre-encoding is required. Thus the presentation time of the last Capsule2-2′ in Bridge-VOB 304 (that is, the Capsule containing the last TSpacket in the Bridge-VOB 304) must be greater than or equal to 0.4 sec.and less than or equal to 1 sec. This also applies when the last Capsulein the Bridge-VOB 304 is not a complete Capsule.

If the last Capsule 2-2′ at the end of the Bridge-VOB 304 is anincomplete Capsule, the video presentation time of a logically completeCapsule must be greater than or equal to 0.4 sec. and less than or equalto 1 sec. even though the first half of the Capsule, which is the lastCapsule recorded in the Bridge-VOB 304, and the second half of theCapsule, which is the Capsule recorded from return_from Bridge_SPN toVOB #2 (302), are stored in separate files.

Furthermore, the presentation time of the first Capsule 1-3′ in theBridge-VOB 304 (that is, the Capsule containing the first TS packet inthe Bridge-VOB 304) must be greater than or equal to 0.4 sec. and lessthan or equal to 1 sec. in order to maintain compatibility with the DVDstandard.

In addition, the last Capsule 1-2 in the VOB #1 before the seamlessconnection must also be a complete Capsule. This is to enable high speedTS2PS conversion of the VOB before the seamless connection withoutdropping AV information at the seamless connection.

A complete Capsule must meet the following conditions.

1) The Capsule must start with a Tip packet (that is, inclusion of a Tippacket means the start of a Capsule).

2) The Capsule contains one or more GOPs.

3) The audio stream and video stream are completely contained within theCapsule. Each stream starts from the first byte in an access unit in theCapsule and ends at the last bye of an access unit.

4) The video stream in the Capsule starts with an I-picture following asequence_header_code and group_start_code.

5) The time difference between the SCR derived from the lastMultiplexing Unit in the preceding Capsule and the PCR of the Tip packetin the following Capsule must be greater than or equal to 43886/27 Msec.if the last Tip packet is in the same STC sequence.

(This is constraint to assure that when converting Capsule N+1 to VOBUN+1 the transfer ending time of the N-th VOBU converted from Capsule Nis before the transfer start time of VOBU N+1 converted from CapsuleN+1.)

6) The difference in the arrival time of the Tip packet and the firstsuccessive packet containing an audio or video stream must be 43886/27Msec. or more.

(This is constraint to assure that there is a sufficient time gap foradding a Navi Pack (if DVD-Video) or an RDI Pack (if DVD-VR) to thebeginning of the VOBU when converting a Capsule to a VOBU.)

7) Except for the last complete Capsule in a continuous STC sequence,the presentation time of video data in the Capsule must be 0.4 sec. to1.0 sec.

The presentation time of video data in the last complete SESF Capsule ina continuous STC sequence is less than or equal to 1.0 sec. whenencode_condition=01b, and 0.4 sec. to 1.2 sec. whenencode_condition=11b.

8) The STC must be continuous within a Capsule.

9) The highest bit in the program_clock_reference_base (33 bits long) inthe adaptation_field ( ) of the transport packet must be 0b.

FIG. 93 shows an example of a seamless connection whereconnection_condition=3 and encode_condition=01b.

As with the case shown in FIG. 92, the presentation time of the Capsule2-2′ containing the last TS packet in Bridge-VOB 304 must also begreater than or equal to 0.4 sec. and less than or equal to 1 sec.regardless of whether it is a complete Capsule in order to enable highspeed conversion to a DVD-VR stream. The presentation time of theCapsule 1-3′ containing the first TS packet in the Bridge-VOB 304 mustalso be greater than or equal to 0.4 sec. and less than or equal to 1sec. in order to enable high speed conversion to a DVD-VR stream. Inaddition, Capsule 1-4′ immediately before the seamless connection (witha presentation time of 1.0 sec. or less because it is the last completeCapsule in the STC sequence) and Capsule 2-1′ immediately after theseamless connection must also be complete Capsules. If these conditionsare met, the conditions of the DVD standard can be met withoutre-encoding in format conversion from a Constrained SESF to MPEG-2program stream.

<Processing Audio Frames Near the Seamless Connection Point>

Processing audio frames near the seamless connection during a formatconversion (“TS2PS conversion”) from the BD Standard to the DVD standardis described next.

In the BD Standard, the two VOBs at the seamless connection must beencoded to include the respective audio samples with a presentation timeat seamless presentation time tc (that is, so that there is no audiogap) as shown in FIG. 94A. In the DVD standard as shown in FIG. 94B,however, the VOB must be encoded at the seamless connection point sothat there is an audio gap including seamless presentation time tc.

Therefore, during TS2PS conversion of a Constrained SESF including aseamless connection point, overlapping audio frames a6 and a7 shown inFIG. 94A must be deleted and an audio gap inserted as shown in FIG. 94B.When converting the seamlessly connected VOB in the second half (theVOBs indicated by hatching in FIG. 94) by deleting an audio frame, thePTS of the audio pack must be modified and adjusted to audio frame a8.Alternatively, the PTS of the audio pack can be appropriately shifted toeliminate the overlap instead of deleting the overlapping audio frame.

Alternatively instead of providing an audio gap, as shown in FIG. 95B,the overlapping audio frames a6 and a7 may be deleted, and an audioframe a8′ that is re-encoded for seamless playback with audio frame a5may be inserted to the beginning of the following VOB, so that an audiogap is not left. However, this causes the presentation time of all audioframes following the audio frame a8′ to shift. Thus, a separate processto advance the PTS of the audio packs containing those audio frames by(t4−t3) is required in this case. The audio pack PTS can also beappropriately shifted to remove any overlap instead of deleting theoverlapping audio frames even when an audio gap is not present.

Processing audio frames when converting from the BD Standard to the DVDstandard (TS2PS conversion) is described above. When converting from theDVD standard to the BD Standard, an audio gap near the seamlessconnection point must be converted to an overlap.

This is done by adding an audio frame (such as audio frames a6 and a7 inFIG. 94) so that audio data is present in the VOBs at the seamlessconnection time of the video stream (time tc in FIG. 94). The addedaudio frames may be audio frames providing no sound.

The number of added audio frames is at most one frame to both theleading VOB and the following VOB. This is because an audio gap in theDVD standard has time length of one frame or less, and both VOBsconnected seamlessly can be assured of having audio data at seamlessconnection time tc by adding one frame. If the VOB already has audiodata at time tc, adding an audio frame to that VOB is not necessary.

<Time Stamp Offset to be Considered at the Seamless Connection>

The offset that should be considered when calculating the time stampduring a TS2PS conversion of seamlessly connected VOBs is describednext.

The DVD-Video standard requires that SCR=0 in the first NV_PCK(navigation pack) in each VOB. This is because each VOB is fed to thedecoder (system target decoder) starting at 0 on the MPEG STC time base.However, this is not assured by recording system standards that allowediting such as deleting the leading part. Thus the SCR of the firstpack in the converted VOB can be made to start from 0 by adding anoffset of a predetermined amount to the MPEG time stamps (SCR/PCR, PTS,DTS) during stream conversion.

An operation for determining this offset is described next withreference to FIG. 96. FIG. 96 shows an example of seamlessly connectinga preceding stream (corresponding to a VOB) containing Capsule 1 andCapsule 2 with a following stream containing Capsule 3 and Capsule 4.Capsule 1 and Capsule 2 correspond respectively to VOBU1 and VOBU2, andCapsule 3 and Capsule 4 correspond respectively to VOBU3 and VOBU4.

To convert one VOB (MPEG-2 transport stream) to one VOB (DVD-VideoMPEG-2 program stream), it is sufficient to reset the SCR to the SCRvalue acquired by the previous SCR operation (FIG. 72) minus offset-1.Regarding PTS and DTS, it is also sufficient to uniformly reset them tothe previous (before conversion) PTS or DTS minus offset-1. A differentoffset (offset-2) is set, which is used for converting two VOBs (MPEG-2transport stream) to one VOB (MPEG-2 DVD-Video program stream). In theexample shown in FIG. 96, offset-2 is the offset for connecting VOBU 3chronologically continuously to VOBU 2.

When not converting to a DVD-Video MPEG-2 program stream (such as whenconverting to a DVD-VR MPEG-2 program stream), offset-1 may be set toany desired value (for example, 0) because the SCR of the beginning packin the VOB does not have to be set to 0.

As shown in FIG. 96, when TS2PS converting the VOB before the seamlessconnection point, an SCR shifted by offset-1 from the SCR acquired bythe above calculation may be used. When TS2PS converting the VOB afterthe seamless connection point, an SCR shifted by offset-2 so that thepresentation ending time of the video frame of the leading VOB overlapsthe presentation start time of the first video frame in the VOB afterthe seamless connection point, or offset-1 can also be used for the VOBafter the seamless connection point if converting to two VOBs on bothsides of the seamless connection point. offset-1 and offset-2 areobtained as follows.

offset−1=PCRtip1

offset−2=FVFPST3−(FVFPST2−offset−1+presentation time of all video framesin VOBU2)

As described above, offset-1 is required for conversion to a DVD-VideoMPEG-2 program stream, but is not required for conversion to a DVD-VRMPEG-2 program stream. In addition, offset-2 is required for the secondVOB when converting two VOBs to one VOB, but is not required if the VOBsare not linked during conversion.

Using offset-1 from the above equation enables setting the SCR to 0 inthe first pack (NV_PCK or RDI_PCK) of the first VOBU (VOBU3 in FIG. 96C)in the VOB on the leading side of the seamless connection.

Using offset-2 from the above equation enables supplying the SCR of thefirst pack (NV_PCK or RDI_PCK) of the first VOBU (VOBU3 in FIG. 96C) inthe VOB on the following side of the seamless connection on the STC timebase continuing from the last pack in the VOB on the leading side of theseamless connection. As a result, TS2PS conversion to one VOB can beachieved.

<TS2PS Conversion of a Seamlessly Connected Constrained SESF>

The process for TS2PS conversion of two VOBs seamlessly connected inConstrained SESF is described next with reference to FIG. 97 to FIG.100.

FIG. 97 describes the process for seamlessly connected VOBs whenconnection_condition=4, and FIG. 98 to FIG. 100 describe the process forseamlessly connecting VOBs when connection_condition=3 (that is, aseamless connection using a Bridge-VOB). In both cases, the conversionis based on the previously described TS2PS conversion process that isused when a seamless connection is not made, and includes a process forcalculating the time stamp based on an offset and a process for deletingoverlapping audio frames.

The TS2PS conversion process for seamlessly connecting two VOBs whenconnection_condition=4 is described with reference to FIG. 97.

Whether there are any overlapping audio frames is first determined, andthe overlapping audio frames are deleted (S301) when the overlapping ispresent. In FIG. 94, for example, audio frames a6 and a7 are deleted.The details of this process are described below.

It is easy and preferable to accomplish determining whether to deleteoverlapping audio frames at the same time of stream conversion. Thepresentation end time (t2) of the audio data in the VOB before theseamless connection point tc is first determined. The presentation endtime (t2) is calculated as described below from the PTS value (PTSp) ofthe last audio PES packet in the VOB before the seamless connection, thedata size (Lpes bit) of the audio stored in the payload of the PESpacket, the data size (Lfrm bit) of the one audio frame stored in thesame payload, and playback time length (the Dfrm clock in 90 kHz units).

t2=PTS+(Lpes/Lfrm)*Dfrm(unit=90 kHz clock)

For brevity below, an integer number of fixed bit rate audio frames areassumed to be stored in the PES packet.

Next, the presentation start time (t1) of audio data in the VOB comingchronologically after the seamless connection point tc is acquired. Thepresentation start time (t1) is the PTS value (PTSs) of the first audioPES packet in the following VOB.

t1=PTSs(unit=90 kHz clock)

If t2<tc<t1, it is determined that there is an audio gap, which meansthe audio frames do not overlap. In this case, the process for adding anaudio gap is therefore not needed, and the conversion process can be runas described above.

However, if t1−t2>Dfrm, the audio gap is longer than one frame, andaudio frames can be therefore added until t1−t2<Dfrm.

Furthermore, if t2=tc=t1, there is neither an audio gap nor an overlap,there is therefore no need to either add or delete audio frames, and theconversion process can be run as described above.

If none of these situations apply, there is an audio overlap at theseamless connection, and audio frames are removed in a range satisfyingt1−t2<Dfrm during the conversion in order to eliminate the overlap. Inorder to remove audio frames, exception handling is required to set thePES_packet_length denoting the PES packet data size, and the PTS fieldvalue denoting the PTS of the first audio frame to correct values.

It should be noted that one method of removing audio frames is describedabove, but other methods can be alternatively used to remove overlappingaudio. For example, an overlap can be removed by shifting all audio PTSvalues in the VOB after the seamless connection point to a time that isgreater than or equal to (t2−t1) and less than (t2−t1+Dfrm) laterchronologically.

Returning to FIG. 97, after removing the audio frame overlap, it isdetermined whether the two VOB being seamlessly connected are to begenerated as two separate VOBs after conversion or as one continuous VOB(S302). If “Yes” (two VOBs are created), the VOB before the seamlessconnection and the VOB after the seamless connection point areseparately converted to an MPEG-PS, and two VOB are ultimately created.If “No”, the VOB before the seamless connection point and the VOB afterthe seamless connection point are converted to an MPEG-PS and thencoupled to create one VOB.

If two VOBs are created by conversion (S302 returns yes), it isdetermined whether the VOB are to be converted to the DVD-Video orDVD-Video Recording standard (S303). If converting to the DVD-Videostandard (S303 returns yes), offset-1 is derived as described above andTS2PS conversion is applied while correcting the time stamp usingoffset-1 (S304). If converting to the DVD-Video Recording standard (S303returns no), TS2PS conversion is applied without time stamp correction(S307).

When TS2PS conversion of the two VOBs ends (S305 returns yes), the twoconverted VOBs are registered in the PGC management information (PGC) sothat they are seamlessly connected (S306). This is done by, for example,setting the connection_condition (connection_code) of the VOBI in theVOB following the seamless connection point to 4, which denotes aseamless connection.

If two VOBs are not created by the conversion process (step S302 returnsNo), offset-1 and offset-2 are determined, and TS2PS conversion isapplied while correcting the time stamps using offset-1 and offset-2(S309). When TS2PS conversion of the two VOB ends (S310 returns Yes),the two converted VOBs are linked and registered as one VOB in themanagement information (PGC) (S311).

The converted VOBs and the management information are then recorded to acontiguous data area (CDA) of the information recording medium to enablecontinuous playback (S308), and the process then ends.

With reference to FIG. 98 to FIG. 100, the TS2PS conversion process fortwo VOB seamlessly connected (seamless connection through a Bridge-VOB)when connection_condition=3 is described next.

First it is determined whether there are any overlapping audio frames,and the overlapping audio frames are deleted (S321) when the overlappingaudio frames area present. Next it is determined whether the two VOBsbeing seamlessly connected are to be generated as two separate VOBs oras one continuous VOB in conversion (S322).

If two VOBs are created finally (S322 returns Yes), it is determinedwhether the VOB are to be converted to the DVD-Video or DVD-VideoRecording standard (S323). If converting to the DVD-Video standard (S323returns Yes), offset-1 is derived and TS2PS conversion is applied usinga Bridge-VOB while correcting the time stamp using offset-1 (S324). Ifconverting to the DVD-Video Recording standard (S323 returns no), TS2PSconversion is applied through a Bridge-VOB without time stamp correction(S327).

When TS2PS conversion of the two VOBs ends (S325 returns yes), the twoconverted VOB are registered in the management information (PGC) so thatthey are seamlessly connected (S326). The two converted VOBs andmanagement information are then recorded to a contiguous data area (CDA)of the information recording medium to enable continuous presentation(S328), and the process then ends.

If step S322 returns No, it is determined whether three VOBs includingthe two VOB being seamlessly connected and the Bridge-VOB are to becreated separately after conversion, or whether one continuous VOB is tobe created (S329). If three separate VOB are created by conversion (S329returns yes), the process shown in FIG. 99 is run. If the three VOB areto be linked into a single VOB after conversion (S329 returns no), theprocess shown in FIG. 100 is run.

The process shown in FIG. 99 is described next.

First, it is determined whether VOBs are converted to the DVD-Videostandard or the DVD-Video Recording standard (S331).

When converting to the DVD-Video standard (S331 returns yes), if the VOBto be converted is not a Bridge-VOB (S332 returns no), offset-1 isdetermined and TS2PS conversion is applied to the VOBs while correctingthe time stamps using offset-1 (S334). If the VOB to be converted is aBridge-VOB (S332 returns yes), offset-1 and offset-2 are determined, andthe Bridge-VOB is TS2PS converted while correcting the time stamps usingoffset-1 and offset-2 (S333).

When converting to the DVD-Video Recording standard (S331 returns no),if the VOB to be converted is not a Bridge-VOB (S337 returns no), TS2PSconversion is applied to the VOB (S339). If the VOB to be converted is aBridge-VOB (S337 returns yes), offset-1 and offset-2 are determined, andTS2PS conversion is applied to whole Bridge-VOB while correcting thetime stamps using offset-1 and offset-2 (S338).

When TS2PS conversion of the three VOBs ends (S335, S340 returns yes),the three converted VOBs are registered in the management information(PGC) as being seamlessly connected (S336). It will be obvious that whenconverting to three VOBs the converted portions of the three VOBs mustbe aligned by Capsule unit. Otherwise, S329 cannot return Yes and theprocess continues from the No branch.

The process shown in FIG. 100 is described next. First it is determinedwhich of the DVD-Video standard and the DVD-Video Recording standard isa target of the conversion (S351).

When converting to the DVD-Video standard (S351 returns yes), if the VOBto be converted is not a Bridge-VOB (S352 returns no), offset-1 isdetermined and TS2PS conversion is applied to VOB while correcting thetime stamps using offset-1 (S354). If the VOB to be converted is aBridge-VOB (S352 returns yes), offset-1 and offset-2 are determined, andTS2PS conversion is applied to whole Bridge-VOB while correcting thetime stamps using offset-1 and offset-2 (S353).

When converting to the DVD-Video Recording standard (S351 returns no),if the VOB to be converted is not a Bridge-VOB (S358 returns no), TS2PSconversion is applied to the VOB (S360). If the VOB to be converted is aBridge-VOB (S358 returns yes), offset-1 and offset-2 are determined, andTS2PS conversion is applied to whole Bridge-VOB while correcting thetime stamps using offset-1 and offset-2 (S359).

When TS2PS conversion of the three VOBs ends (S355, S361 returns yes),the three converted VOBs are linked into a single VOB (S356). The oneconverted VOB is then registered in the management information (PGC)(S357).

The basic flow of this process is described above, but in order to linkthe three converted VOBs into one continuous VOB, if step S351 returnsyes, a separate process is required to add the offset to the time stampusing a method similar to that used with offset-2 so that the singlelinked VOB has a continuous time stamp starting from SCR=0. Furthermore,even if step S351 returns no, a separate process is required to add theoffset to the time stamp using a method similar to that used withoffset-2 so that the single linked VOB has a continuous time stamp.

The method described above enables TS2PS conversion of a system streamincluding a seamless connection.

The conversion process shown in FIG. 97 to FIG. 100 is applied to thestream on the recording medium 100 by specifying conversion portion bythe user using the user interface 222 shown in FIG. 20, and controllingthe drive 221 by the system controller 212 using the information on theconversion portion.

Processes for re-encoding data at the seamless connection are alsoapplied to the stream on the recording medium 100 by specifying the twoVOBs for seamless connection using the user interface 222 shown in FIG.20, and controlling the drive 221 by the system controller 212, in thesame way as in the conversion process.

TS2PS conversion can thus be easily executed at high speed even whenseamlessly connecting the content streams by defining conditions for theConstrained SESF for seamless connection and defining the conversionmethod thereof.

When self-encoding externally input AV data to an MPEG transport streamformat, the data recording apparatus and method of the inventiondescribed above can thus efficiently encode and decode the streams whilemaintaining decoder compatibility.

Furthermore, because user private data can be stored to the streamsrecorded to the data recording medium, the added value of recordedcontent in the MPEG transport stream format can be increased.

Moreover, because the stream is multiplexed in block units of 2 KB orless so that an MPEG_TS recorded to a data recording medium can beefficiently and easily converted to an MPEG_PS, the conversion fromMPEG_TS to MPEG_PS including seamless connection point can be veryeasily achieved without considering buffer management.

Although in the above description, inverse conversion from MPEG-PS toMPEG-TS is not described, it can be similarly considered as inversion ofTS2PS conversion. For example, it can be considered that one PS pack isconverted to a plurality of continuous TS packets, increment of ATSbetween the plurality of continuous TS packets is fixed value, and suchinformation is stored in a disk or stream.

When titles of clips of MPEG-PS (program information indicatingcontents, etc.) are stored in SIT packet and are converted to MPEG-TS,it becomes possible to display original program titles by a decoder suchas STB.

Although the present invention has been described in connection with thespecific embodiments thereof with reference to the accompanyingdrawings, it is to be noted that various changes and modifications willbe apparent to those skilled in the art. Thus the scope of the presentinvention is not limited to the specific disclosure but limited to theappended claims. The present application is related to Japanese PatentApplication No. 2004-112980, filed on Apr. 7, 2004, which is expresslyincorporated herein by reference.

INDUSTRIAL APPLICABILITY

According to the invention, a format conversion from a first stream to asecond stream can be easily and rapidly achieved. Especially, theconversion to a stream connected seamlessly can be easily achieved whilemaintaining seamless playback function. Thus the invention can beapplied to a information recording medium having a format conversionfunction from a first stream (for example, MPEG transport stream) to asecond stream (for example, MPEG program stream).

1. An information recording medium for storing video information andaudio information encoded into a system stream together with associatedmanagement information, wherein the system stream is allowed to have afirst format (TS) and a second format (PS), the first format (TS) havinga packet structure for storing data segmented in packets, the secondformat (PS) having a pack structure for storing data segmented in packs,the first format (TS) is allowed to have a constrained format used forconverting the system stream from the first format (TS) to the secondformat (PS), according to the constrained format, a predetermined numberof packets are grouped and managed as a multiplexing unit whichcorresponds to the pack of the second format, and the system stream ismanaged in a data management unit (Capsule) which includes a pluralityof multiplexing units, the management information contains playbacksequence information (PGC) indicating a playback sequence of the systemstream, the playback sequence information is described by a combinationof playback portions (Cells) corresponding to one or a plurality ofcontinuous system streams; the management information containsconnection information (connection_code) for each playback portion, theconnection information indicating whether each playback portion isplayed back seamlessly from the playback portion in the previousplayback sequence, when the connection information indicates seamlessplayback, a third system stream (Bridge-VOB) including a part of each ofthe two seamlessly connected system streams is used to enable seamlessplayback, and the third system stream is recorded according to theconstrained format so that the playback time of the video information inthe data management unit (Capsule) containing the last packet of thethird system stream is greater than or equal to 0.4 second and less thanor equal to 1 second.
 2. An information recording apparatus for encodingaudio information and video information into a system stream andrecording the system stream with associated management information to aninformation recording medium, wherein the system stream is allowed tohave a first format (TS) and a second format (PS), the first format (TS)having a packet structure for storing data segmented in packets, thesecond format (PS) having a pack structure for storing data segmented inpacks, the first format (TS) is allowed to have a constrained formatused for converting the system stream from the first format (TS) to thesecond format (PS), according to the constrained format, a predeterminednumber of packets are grouped and managed as a multiplexing unit whichcorresponds to the pack of the second format, and the system stream ismanaged in a data management unit (Capsule) which includes a pluralityof multiplexing units, the management information contains playbacksequence information (PGC) indicating a playback sequence of the systemstream, the playback sequence information is described by a combinationof playback portions (Cells) corresponding to one or a plurality ofcontinuous system streams, the management information containsconnection information (connection_code) for each playback portion, theconnection information indicating whether each playback portion isplayed back seamlessly from the playback portion in the previousplayback sequence, when the connection information indicates seamlessplayback, a third system stream (Bridge-VOB) including a part of each ofthe two seamlessly connected system streams is used to enable seamlessplayback, the information recording apparatus comprises: a firstencoding section that applies a specific encoding process to the videoinformation and audio information to generate a video elementary streamand an audio elementary stream based on the first format (TS); a secondencoding section that applies system-encoding to multiplex the videoelementary stream and the audio elementary stream into a system streambased on the first format (TS); and a controller that controls the firstand second encoding sections, and the controller controls the first andsecond encoding sections so that the playback time of the videoinformation in the data management unit (Capsule) at the end of thethird system stream is greater than or equal to 0.4 second and less thanor equal to 1 second.
 3. A method for encoding audio information andvideo information into a system stream and recording the system streamwith associated management information to an information recordingmedium, wherein the system stream is allowed to have a first format (TS)and a second format (PS), the first format (TS) having a packetstructure for storing data segmented in packets, the second format (PS)having a pack structure for storing data segmented in packs, the firstformat (TS) is allowed to have a constrained format used for convertingthe system stream from the first format (TS) to the second format (PS),according to the constrained format, a predetermined number of packetsare grouped and managed as a multiplexing unit which corresponds to thepack of the second format, and the system stream is managed in a datamanagement unit (Capsule) which includes a plurality of multiplexingunits, the management information contains playback sequence information(PGC) indicating a playback sequence of the system stream, the playbacksequence information is described by a combination of playback portions(Cells) corresponding to one or a plurality of continuous systemstreams, the management information contains connection information(connection_code) for each playback portion, the connection informationindicating whether each playback portion is played back seamlessly fromthe playback portion in the previous playback sequence, when theconnection information indicates seamless playback, a third systemstream (Bridge-VOB) including a part of each of the two seamlesslyconnected system streams is used to enable seamless playback, theinformation recording method comprises: applying a specific encodingprocess to the video information and audio information to generate avideo elementary stream and an audio elementary stream based on thefirst format (TS), and multiplexing and system encoding the videoelementary stream and audio elementary stream based on the first format(TS) to generate the system stream, and the encoding process is appliedso that the playback time of the video information in the datamanagement unit (Capsule) at the end of the third system stream isgreater than or equal to 0.4 second and less than or equal to 1 second.